atariry

Just recently I was lucky enough to buy 3 broken/faulty Atari STs very cheaply. TBH I was only interested in one, in order to salvage a dome from the keyboard, because I lost a dome when I disassembled the keyboard of my current STe for cleaning, doh! However the seller offered them all to me for such a low price I couldn't refuse. Now I already have an ST and mono monitor which I bought a year or so ago to try to copy files from my saved collection of ST floppies. Ironically last night, while moving things on my soldering work startion, I found the missing keyboard dome! I don't really want or need these STs, and I am not interested in repairing in order to sell on Ebay, so I don't want to pour too much time into working on them. I am posting because I hope some people might be interested in whether I manage to repair any of them. For sure one will be given to a friend, and my idea is to install EMUTOS in another (assuming that I can get any of them repaired). I sort of assume that I can get one or two working STs out of the three. So when I collected them it was clear that they were going to be faulty. The floppy disk drive was missing from two of the STs. All three keyboards had at minimum missing keycaps and/or broken key shafts. The cases themselves were all 520STFMs and were in very good shape. On case had minor damage at the rear left near the cart port. The other had been hacked to take a Gotek. All three were not badly yellowed. On had no sticker on the bottom. Top Atari ST - came with no ROMs (pictures above is after a swap over). C070789-001 Rev B. 1Mbyte of DIL RAM. Middle Atari ST - 2 ROMs. C070789-001 Rev F2. 512k of DIL RAM. Missing the floppy disk controller IC (socketed). Bottom Atari ST - came with 6 ROMs (pictured after they were installed in the other PCB). 512k of SMD RAM. IMP chipset for GLUE/MMU. I have already posted about repair of the switch mode PSUs (WIP). I know that replacements can be bought, but I don't really want to sink any money into the repair. If I can repair any of the PSUs using parts from my spares box, then that will be a bonus. BTW I am well aware of the dangers of working on switch mode PSUs due to the high and dangerous voltages. I will post updates in the hope some readers are interested. --atariry

While I have repaired switch mode PSUs previously and get more life out of older electronic gadgets, in all cases I simply replaced the obviously bulging caps. I was lucky. Faults are not always as easy as this to fix. If you have the spares to hand it is usually a quick job to replace bulging caps as a quick look and see.

Well it's my own risk. I did mention that I am based in the UK. So although I have ordered from the US in the past, postal costs and import charges and duty usually make it uneconomical. There are UK Ebay sellers selling reconditioned PSUs, however I really don't want to pour any money into this project as I have no intention of selling any repaired item. I'll keep it or pass it on to a friend. Worst case, I throw all 3 STs away if they are too far gone, however having said that two show signs of life when powered from a lab PSU. BTW the need for an isolation transformer is so that I can use an oscilloscope. You can't just use a normal ground pin and "probe" into a switch mode PSU.

Thank you for the posting the schematic. I do already have this version, but not the C0707800 one. Nevertheless by examination of the components, I am pretty confident they are identical, perhaps some minor differences. At the moment I need to buy or make an isolation transformer. I have used a multimeter just to quickly check resistor values in the HV side of the design. They are all OK. I also used the diode function to check the base-emitter and base-collector diodes in each of the two transistors. As far as I can tell they are OK, with no shorts or opens. Just FYI, I would heartily recommended the YouTube channel called "DiodeGoneWild". He has done a lot of videos on switch mode power supply operation, both small 5V USB types and larger 200W types. He explains really well how they work. The Atari design resembles some of the transistor only designs which he has covered during tear downs. I need to go back and see some of these videos to remind myself, but Q2 oscillates and pulses the primary of T2, with feedback via the PC817 opto-isolator and control of the frequency of oscillation by Q1 affecting Q2. There isn't too much to go wrong. Of my three STs, when I power them up from a lab PSU, having removed the switch mode PSUs, two of the three partially work (one is missing the FDC chip), the third had no ROM chips, but when swapped over this one is dead. It could have been that this first PSU came from that ST, and so it could very well be OK, just when I first tested the third ST it was never going to do anything. I don't want to get controversial, but there is actually some debate about replacing old electrolytic capacitors. Some people propose always replacing every electrolytic capacitor, but I think I am from the school of only replacing those which have bad ESR. Perhaps I'm just a bit lazy 🙂 . I do have a selection of capacitors, some new, and some unsoldered from broken switch mode PSUs. I ought to get an ESR meter, but I would use it so infrequently I haven't bothered. Thank you for the pointer to the other forum. I am aware of this Atari resource, and found that they sell recapping kits through their shop, but hopefully I will find the correct parts in my "junk" box.

Just to clarify. 1) I am based in the UK. 2) I would like to see if I can fix the PSUs myself. I already have various parts such as caps, resistors and bridge rectifiers in my "junk" box. If any transistors are blown, then I would need to buy replacements, because they are not common types. I would appreciate any hints, such as "replace that RIFA cap immediately". AFAIK the big blue class Y cap is not a brand known for "letting out the smoke".

I did a search of the forum and didn't see many topics on the subject of repair of the STs (internal) power supply. Just yesterday I bought three broken Atari STs. They had been cannibalised for various items, such as floppy disk drive, FDC chip, and keycaps. They all had internal PSUs, but it was clear that they were not working. BTW, I am an experienced electronics engineer. I am aware of the dangers of working on mains powered circuits such as switch mode PSUs. I do have a reasonable grasp of how they operate. I also have desoldering equipment and test equipment such as oscilloscopes. So no need to warn me about trying to work on these circuits. One of the PSUs does have obvious bulging capacitors, a sure sign of failure. I have fixed other PSUs in other equipment over the years by simply replacing these type of failing caps. Looking at the first PSU, it is type C070800-002. I have the schematics for what appears to be the close relative the C070798. I do not have schematics for this specific version, but at first glance my PSU appears to be pretty much identical. Does anyone have a pointer to my specific version? The caps on this one appear OK (no bulging). There is black charring on the bottom of the PCB around the PCB pads of resistor R4 a 330ohm 1W resistor. It must get pretty toasty! It is part of a snubber circuit across the primary of the main transformer. I have no idea if this is normal or perhaps a result of the side effect of the failure of the PSU. Also does anyone have any pointers to any videos or forum postings where operation of the PSU might have been described together with scope waveforms shown? I have been away from the Atari ST scene for quite a while, so it will be fun trying to see if I can get any of the three poorly STs back into working condition.

Wow! I have never come across your web pages before. Looks like an excellent and well organised source of information. What is the home page? From the one with the title "The Serious Computerist" I couldn't find out how to find the drive pages. The link above does work, but I couldn't see how they are linked. I simply wanted to bookmark a single page.

So I recently got interested in sound ICs, as a consequence of checking some parts bought via Ebay were genuine. I found about about VGM file format, which allows tunes to be played by various sound chips. So I bought a cheap non working Sega Megadrive for the purpose of harvesting the YM2612 sound chip. The intention was to connect it up to an Arduino (there are many projects on the web) in order to play Megadrive tunes from VGMs. Before I removed the sound IC, I was interested to see if I could figure out what was wrong with the unit. The reset switch was faulty, but that was a simple fix. Using a scope to look at signals around the MC68000, HALT and RESET have activity when the reset button is pressed. There is good 5V power and a good clock. Looking at some of the other pins I see 4 low going pulses of LDS and UDS, then no more activity. My guess is that these pulses are for the initial stack pointer and instruction counter (both 32 bit) which is 4 16-bit reads. I am a little uncertain, but perhaps the CPU halts if these are invalid in some way? I have attached some waveforms. it was done a few weeks ago, so please excuse my faulty memory! I think that notRESET is the yellow trace; notHALT is the cyan trace; and two of the top four traces are UDS and LDS. So the CPU does appear to halt. Here I admit that there was no cartridge inserted. I may have been thinking that there was some boot ROM, as I read something about TMSS (sp?). Nevertheless when I inserted a cartridge nothing changed. I would appreciate any advice as to what to try next or any pointers to sites which have detailed technical details about the boot process. For example where are the initial stack pointer and instruction counter read from: built in ROM; or the cartridge?

Hello, I'm late to this thread... I just googled for this monitor in the UK. Firstly I note that a model SE2722HX appears (note the 'X'). Has anyone tested this version? Scan dot co dot uk who is my usual goto supplier, has the monitor listed at £220. Visiting the Dell UK website, the price is £115. There are various other sites with prices between the above two. The Dell price is very tempting, I must say 😁

Many thanks ? I didn't know such quality schematics existed, even in the official manuals.

All good points, so... 1) POKEY and PIA register address defines are there for future use. I do intend to add these chips in the future. Currently they are not wired or plugged in, but there is room for them on the breadboards. 2) some code left over from cut and pasting from OS source. That/this line serves no purpose (VBWAIT: lda ANTICrVCOUNT ;WAIT FOR NEXT VBLANK BEFORE MESSING). 3) I am not using NMI or IRQ, but didn't want to leave the vectors empty. To keep the code as short and simple as possible I write directly to hardware and I have not implemented shadow registers. However your code could be very helpful for a future revision. Thank you. The code was more or less cut and pasted from a disassembly of the OS. When I took a look at the 5200 OS source code I was rather shocked at the similarity. NOTE: my hardware has no video circuitry. I firstly want to view the outputs of GTIA on a scope and then later connect them to the FPGA. I will possibly add the original video combiner circuity just to try the various component changes and tweaks found in various forum posts, just to see how clean I can get the picture on my Dell. As I mentioned the picture from my 130XE is horrendous with very visible jail bars. I am no analogue expert, but I suspect part of the 130XE problem was caused by signal routing and grounding. Next step is to add the 32 channel logic analyser (known as "SUMP"), based on a cheap Chinese Spartan6 FPGA board, which incorporates 5V level shifters, bought for only $15 on AliExpress (google - RTV901T). I am still in the process of porting the code to this platform. Given how expensive even 16 channel logic analysers are, this is a super cheap solution.

I used the Altirra emulator and replaced the system ROM with my own code assembled into a 16k binary with origin at $c000. Here is the code in case anyone is interested... ; ; Simple initialisation and display list code for ; "Atari on a Breadboard" project ; Uses the AS65 6502 assembler by Frank Kingswood. ; ; 05-Mar-2020 : atariry ; - First write. Add hardware location defines. ; - Start to add custom chip init code. ; 08-Mar-2020 : atariry ; - Add character set definitions. ; - Make sure all writes are to hardware registers. ; ;;;;;;;;; ; POKEY ; ;;;;;;;;; POKEY = $D200 POKEYrPOT0 = POKEY+0 POKEYrPOT1 = POKEY+1 POKEYrPOT2 = POKEY+2 POKEYrPOT3 = POKEY+3 POKEYrPOT4 = POKEY+4 POKEYrPOT5 = POKEY+5 POKEYrPOT6 = POKEY+6 POKEYrPOT7 = POKEY+7 POKEYrALLPOT = POKEY+8 POKEYrKBCODE = POKEY+9 POKEYrRANDOM = POKEY+10 POKEYrPOTGO = POKEY+11 POKEYrSERIN = POKEY+13 POKEYrIRQST = POKEY+14 POKEYrSKSTAT = POKEY+15 ; POKEYwAUDF1 = POKEY+0 POKEYwAUDC1 = POKEY+1 POKEYwAUDF2 = POKEY+2 POKEYwAUDC2 = POKEY+3 POKEYwAUDF3 = POKEY+4 POKEYwAUDC3 = POKEY+5 POKEYwAUDF4 = POKEY+6 POKEYwAUDC4 = POKEY+7 POKEYwAUDCTL = POKEY+8 POKEYwSTIMER = POKEY+9 POKEYwSKRES = POKEY+10 POKEYwSEROUT = POKEY+13 POKEYwIRQEN = POKEY+14 POKEYwSKCTL = POKEY+15 ;;;;;;;; ; GTIA ; ;;;;;;;; GTIA = $D000 GTIAwHPOSP0 = GTIA+0 GTIAwHPOSP1 = GTIA+1 GTIAwHPOSP2 = GTIA+2 GTIAwHPOSP3 = GTIA+3 GTIAwHPOSM0 = GTIA+4 GTIAwHPOSM1 = GTIA+5 GTIAwHPOSM2 = GTIA+6 GTIAwHPOSM3 = GTIA+7 GTIAwSIZEP0 = GTIA+8 GTIAwSIZEP1 = GTIA+9 GTIAwSIZEP2 = GTIA+10 GTIAwSIZEP3 = GTIA+11 GTIAwSIZEM = GTIA+12 GTIAwGRAFP0 = GTIA+13 GTIAwGRAFP1 = GTIA+14 GTIAwGRAFP2 = GTIA+15 GTIAwGRAFP3 = GTIA+16 GTIAwGRAFM = GTIA+17 GTIAwCOLPM0 = GTIA+18 GTIAwCOLPM1 = GTIA+19 GTIAwCOLPM2 = GTIA+20 GTIAwCOLPM3 = GTIA+21 GTIAwCOLPF0 = GTIA+22 GTIAwCOLPF1 = GTIA+23 GTIAwCOLPF2 = GTIA+24 GTIAwCOLPF3 = GTIA+25 GTIAwCOLBK = GTIA+26 GTIAwPRIOR = GTIA+27 GTIAwVDELAY = GTIA+28 GTIAwGRACTL = GTIA+29 GTIAwHITCLR = GTIA+30 GTIArM0PF = GTIA+0 GTIArM1PF = GTIA+1 GTIArM2PF = GTIA+2 GTIArM3PF = GTIA+3 GTIArP0PF = GTIA+4 GTIArP1PF = GTIA+5 GTIArP2PF = GTIA+8 GTIArP3PF = GTIA+7 GTIArM0PL = GTIA+8 GTIArM1PL = GTIA+9 GTIArM2PL = GTIA+10 GTIArM3PL = GTIA+11 GTIArP0PL = GTIA+12 GTIArP1PL = GTIA+13 GTIArP2PL = GTIA+14 GTIArP3PL = GTIA+15 GTIArTRIG0 = GTIA+16 GTIArTRIG1 = GTIA+17 GTIArTRIG2 = GTIA+18 GTIArTRIG3 = GTIA+19 ; GTIArwCONSOL = GTIA+31 ;;;;;;;;; ; ANTIC ; ;;;;;;;;; ANTIC = $D400 ANTICwDMACTL = ANTIC+0 ANTICwCHACTL = ANTIC+1 ANTICwDLISTL = ANTIC+2 ANTICwDLISTH = ANTIC+3 ANTICwHSCROL = ANTIC+4 ANTICwVSCROL = ANTIC+5 ANTICwPMBASE = ANTIC+7 ANTICwCHBASE = ANTIC+9 ANTICwWSYNC = ANTIC+10 ANTICwNMIEN = ANTIC+14 ANTICwNMIRES = ANTIC+15 ; ANTICrVCOUNT = ANTIC+11 ANTICrPENH = ANTIC+12 ANTICrPENV = ANTIC+13 ANTICrNMIST = ANTIC+15 ;;;;;;; ; PIA ; ;;;;;;; PIA = $D300 PIArwPORTA = PIA+0 PIArwPORTB = PIA+1 PIArwPACTL = PIA+2 PIArwPBCTL = PIA+3 ; ; PAGE2 = $0200 CHACT = PAGE2+1 DLIST_DATA = PWRUP DLIST_8BLANK = $70 DLIST_GR0 = 2 DLIST_LOADLMS = $40 DLIST_JUMPWAIT= $41 code org $c000 ;*************************************************************** ; POWER UP ROUTINES START HERE ;*************************************************************** ; PWRUP: sei ;DISABLE IRQ INTERRUPTS cld ;CLEAR DECIMAL FLAG. ldx #$FF txs ;SET STACK POINTER ; ; Clear all regisers of custom hardweare chips ; HARDI: lda #0 tax CLRCHP: sta GTIA,x sta ANTIC,x sta POKEY,x sta PIA,x inx bne CLRCHP ; ; initialise non hardware locations ; lda # hi CHSET sta ANTICwCHBASE lda #2 sta ANTICwCHACTL ; ldx #4 ;LOAD COLOR REGISTERS CLOOP: lda COLRTB,x sta GTIAwCOLPF0,x dex bpl CLOOP ; lda #6 ;PUT GTIA LUM VALUE INTO BACKGROUND REGISTER sta GTIAwCOLBK VBWAIT: lda ANTICrVCOUNT ;WAIT FOR NEXT VBLANK BEFORE MESSING lda # lo DLIST sta ANTICwDLISTL lda # hi DLIST sta ANTICwDLISTH lda #$22 ;34 = 32 (enable DMA) + 2 (standard playfield) sta ANTICwDMACTL ; INFLOOP: jmp INFLOOP ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; COLRTB: db $28,$CA,$94,$46,$00 DLIST: db DLIST_8BLANK,DLIST_8BLANK,DLIST_8BLANK db DLIST_LOADLMS+DLIST_GR0 db lo DLIST_DATA db hi DLIST_DATA db 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2 db DLIST_JUMPWAIT db lo DLIST db hi DLIST ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; org $f000 CHSET: db $00,$00,$00,$00,$00,$00,$00,$00 ;$00 - space db $00,$18,$18,$18,$18,$00,$18,$00 ;$01 - ! db $00,$66,$66,$66,$00,$00,$00,$00 ;$02 - " db $00,$66,$FF,$66,$66,$FF,$66,$00 ;$03 - # db $18,$3E,$60,$3C,$06,$7C,$18,$00 ;$04 - $ db $00,$66,$6C,$18,$30,$66,$46,$00 ;$05 - % db $1C,$36,$1C,$38,$6F,$66,$3B,$00 ;$06 - & db $00,$18,$18,$18,$00,$00,$00,$00 ;$07 - ' db $00,$0E,$1C,$18,$18,$1C,$0E,$00 ;$08 - ( db $00,$70,$38,$18,$18,$38,$70,$00 ;$09 - ) db $00,$66,$3C,$FF,$3C,$66,$00,$00 ;$0A - asterisk db $00,$18,$18,$7E,$18,$18,$00,$00 ;$0B - plus db $00,$00,$00,$00,$00,$18,$18,$30 ;$0C - comma db $00,$00,$00,$7E,$00,$00,$00,$00 ;$0D - minus db $00,$00,$00,$00,$00,$18,$18,$00 ;$0E - period db $00,$06,$0C,$18,$30,$60,$40,$00 ;$0F - / db $00,$3C,$66,$6E,$76,$66,$3C,$00 ;$10 - 0 db $00,$18,$38,$18,$18,$18,$7E,$00 ;$11 - 1 db $00,$3C,$66,$0C,$18,$30,$7E,$00 ;$12 - 2 db $00,$7E,$0C,$18,$0C,$66,$3C,$00 ;$13 - 3 db $00,$0C,$1C,$3C,$6C,$7E,$0C,$00 ;$14 - 4 db $00,$7E,$60,$7C,$06,$66,$3C,$00 ;$15 - 5 db $00,$3C,$60,$7C,$66,$66,$3C,$00 ;$16 - 6 db $00,$7E,$06,$0C,$18,$30,$30,$00 ;$17 - 7 db $00,$3C,$66,$3C,$66,$66,$3C,$00 ;$18 - 8 db $00,$3C,$66,$3E,$06,$0C,$38,$00 ;$19 - 9 db $00,$00,$18,$18,$00,$18,$18,$00 ;$1A - colon db $00,$00,$18,$18,$00,$18,$18,$30 ;$1B - semicolon db $06,$0C,$18,$30,$18,$0C,$06,$00 ;$1C - < db $00,$00,$7E,$00,$00,$7E,$00,$00 ;$1D - = db $60,$30,$18,$0C,$18,$30,$60,$00 ;$1E - > db $00,$3C,$66,$0C,$18,$00,$18,$00 ;$1F - ? db $00,$3C,$66,$6E,$6E,$60,$3E,$00 ;$20 - @ db $00,$18,$3C,$66,$66,$7E,$66,$00 ;$21 - A db $00,$7C,$66,$7C,$66,$66,$7C,$00 ;$22 - B db $00,$3C,$66,$60,$60,$66,$3C,$00 ;$23 - C db $00,$78,$6C,$66,$66,$6C,$78,$00 ;$24 - D db $00,$7E,$60,$7C,$60,$60,$7E,$00 ;$25 - E db $00,$7E,$60,$7C,$60,$60,$60,$00 ;$26 - F db $00,$3E,$60,$60,$6E,$66,$3E,$00 ;$27 - G db $00,$66,$66,$7E,$66,$66,$66,$00 ;$28 - H db $00,$7E,$18,$18,$18,$18,$7E,$00 ;$29 - I db $00,$06,$06,$06,$06,$66,$3C,$00 ;$2A - J db $00,$66,$6C,$78,$78,$6C,$66,$00 ;$2B - K db $00,$60,$60,$60,$60,$60,$7E,$00 ;$2C - L db $00,$63,$77,$7F,$6B,$63,$63,$00 ;$2D - M db $00,$66,$76,$7E,$7E,$6E,$66,$00 ;$2E - N db $00,$3C,$66,$66,$66,$66,$3C,$00 ;$2F - O db $00,$7C,$66,$66,$7C,$60,$60,$00 ;$30 - P db $00,$3C,$66,$66,$66,$6C,$36,$00 ;$31 - Q db $00,$7C,$66,$66,$7C,$6C,$66,$00 ;$32 - R db $00,$3C,$60,$3C,$06,$06,$3C,$00 ;$33 - S db $00,$7E,$18,$18,$18,$18,$18,$00 ;$34 - T db $00,$66,$66,$66,$66,$66,$7E,$00 ;$35 - U db $00,$66,$66,$66,$66,$3C,$18,$00 ;$36 - V db $00,$63,$63,$6B,$7F,$77,$63,$00 ;$37 - W db $00,$66,$66,$3C,$3C,$66,$66,$00 ;$38 - X db $00,$66,$66,$3C,$18,$18,$18,$00 ;$39 - Y db $00,$7E,$0C,$18,$30,$60,$7E,$00 ;$3A - Z db $00,$1E,$18,$18,$18,$18,$1E,$00 ;$3B - [ db $00,$40,$60,$30,$18,$0C,$06,$00 ;$3C - \ db $00,$78,$18,$18,$18,$18,$78,$00 ;$3D - ] db $00,$08,$1C,$36,$63,$00,$00,$00 ;$3E - ^ db $00,$00,$00,$00,$00,$00,$FF,$00 ;$3F - underline db $00,$36,$7F,$7F,$3E,$1C,$08,$00 ;$40 - heart card db $18,$18,$18,$1F,$1F,$18,$18,$18 ;$41 - mid left window db $03,$03,$03,$03,$03,$03,$03,$03 ;$42 - right box db $18,$18,$18,$F8,$F8,$00,$00,$00 ;$43 - low right window db $18,$18,$18,$F8,$F8,$18,$18,$18 ;$44 - mid right window db $00,$00,$00,$F8,$F8,$18,$18,$18 ;$45 - up right window db $03,$07,$0E,$1C,$38,$70,$E0,$C0 ;$46 - right slant box db $C0,$E0,$70,$38,$1C,$0E,$07,$03 ;$47 - left slant box db $01,$03,$07,$0F,$1F,$3F,$7F,$FF ;$48 - right slant solid db $00,$00,$00,$00,$0F,$0F,$0F,$0F ;$49 - low right solid db $80,$C0,$E0,$F0,$F8,$FC,$FE,$FF ;$4A - left slant solid db $0F,$0F,$0F,$0F,$00,$00,$00,$00 ;$4B - up right solid db $F0,$F0,$F0,$F0,$00,$00,$00,$00 ;$4C - up left solid db $FF,$FF,$00,$00,$00,$00,$00,$00 ;$4D - top box db $00,$00,$00,$00,$00,$00,$FF,$FF ;$4E - bottom box db $00,$00,$00,$00,$F0,$F0,$F0,$F0 ;$4F - low left solid db $00,$1C,$1C,$77,$77,$08,$1C,$00 ;$50 - club card db $00,$00,$00,$1F,$1F,$18,$18,$18 ;$51 - up left window db $00,$00,$00,$FF,$FF,$00,$00,$00 ;$52 - mid box db $18,$18,$18,$FF,$FF,$18,$18,$18 ;$53 - mid window db $00,$00,$3C,$7E,$7E,$7E,$3C,$00 ;$54 - solid circle db $00,$00,$00,$00,$FF,$FF,$FF,$FF ;$55 - bottom solid db $C0,$C0,$C0,$C0,$C0,$C0,$C0,$C0 ;$56 - left box db $00,$00,$00,$FF,$FF,$18,$18,$18 ;$57 - up mid window db $18,$18,$18,$FF,$FF,$00,$00,$00 ;$58 - low mid window db $F0,$F0,$F0,$F0,$F0,$F0,$F0,$F0 ;$59 - left solid db $18,$18,$18,$1F,$1F,$00,$00,$00 ;$5A - low left window db $78,$60,$78,$60,$7E,$18,$1E,$00 ;$5B - display escape db $00,$18,$3C,$7E,$18,$18,$18,$00 ;$5C - up arrow db $00,$18,$18,$18,$7E,$3C,$18,$00 ;$5D - down arrow db $00,$18,$30,$7E,$30,$18,$00,$00 ;$5E - left arrow db $00,$18,$0C,$7E,$0C,$18,$00,$00 ;$5F - right arrow db $00,$18,$3C,$7E,$7E,$3C,$18,$00 ;$60 - diamond card db $00,$00,$3C,$06,$3E,$66,$3E,$00 ;$61 - a db $00,$60,$60,$7C,$66,$66,$7C,$00 ;$62 - b db $00,$00,$3C,$60,$60,$60,$3C,$00 ;$63 - c db $00,$06,$06,$3E,$66,$66,$3E,$00 ;$64 - d db $00,$00,$3C,$66,$7E,$60,$3C,$00 ;$65 - e db $00,$0E,$18,$3E,$18,$18,$18,$00 ;$66 - f db $00,$00,$3E,$66,$66,$3E,$06,$7C ;$67 - g db $00,$60,$60,$7C,$66,$66,$66,$00 ;$68 - h db $00,$18,$00,$38,$18,$18,$3C,$00 ;$69 - i db $00,$06,$00,$06,$06,$06,$06,$3C ;$6A - j db $00,$60,$60,$6C,$78,$6C,$66,$00 ;$6B - k db $00,$38,$18,$18,$18,$18,$3C,$00 ;$6C - l db $00,$00,$66,$7F,$7F,$6B,$63,$00 ;$6D - m db $00,$00,$7C,$66,$66,$66,$66,$00 ;$6E - n db $00,$00,$3C,$66,$66,$66,$3C,$00 ;$6F - o db $00,$00,$7C,$66,$66,$7C,$60,$60 ;$70 - p db $00,$00,$3E,$66,$66,$3E,$06,$06 ;$71 - q db $00,$00,$7C,$66,$60,$60,$60,$00 ;$72 - r db $00,$00,$3E,$60,$3C,$06,$7C,$00 ;$73 - s db $00,$18,$7E,$18,$18,$18,$0E,$00 ;$74 - t db $00,$00,$66,$66,$66,$66,$3E,$00 ;$75 - u db $00,$00,$66,$66,$66,$3C,$18,$00 ;$76 - v db $00,$00,$63,$6B,$7F,$3E,$36,$00 ;$77 - w db $00,$00,$66,$3C,$18,$3C,$66,$00 ;$78 - x db $00,$00,$66,$66,$66,$3E,$0C,$78 ;$79 - y db $00,$00,$7E,$0C,$18,$30,$7E,$00 ;$7A - z db $00,$18,$3C,$7E,$7E,$18,$3C,$00 ;$7B - spade card db $18,$18,$18,$18,$18,$18,$18,$18 ;$7C - | db $00,$7E,$78,$7C,$6E,$66,$06,$00 ;$7D - display clear db $08,$18,$38,$78,$38,$18,$08,$00 ;$7E - display backspace db $10,$18,$1C,$1E,$1C,$18,$10,$00 ;$7F - display tab ;;;;;;;;;;; ; VECTORS ; ;;;;;;;;;;; org $fffa dw PWRUP dw PWRUP dw PWRUP This is the resultant display...

Thank you to everyone who has replied. Over the past few days I have updated the Kicad schematic and completed the wiring of all 3 Atari chips (currently no Pokey or PIO). I have also tried to refine my minimal boot, but I am sure that is it incomplete. FYI I have 16k RAM from 0000 to 4000 and 8k ROM from E000 to FFFF. This is emulated by the FPGA, but I have yet to try running the system to find out even if this is working. I used the FPGA as it was easier and quicker than physically wiring up RAM and ROM chips. The FPGA "sees" all address, data and control signals. In theory I could use the FPGA to emulate a Pokey, but for the custom chips I prefer to use real hardware. The end goal is to generate a clean HDMI video stream then wire up the solution to my 130XE whose video is of horrendous quality. Talking about the 5200 which I know has a different memory map to the 400/800, I spotted something which I am sure is well known to Atari experts, that GTIA has a chip select input, so can be anywhere in the memory map, whereas ANTIC already has all 16 address lines, so has the address select range built in. I had to add the address decode for GTIA to the FPGA code. I had a couple of ideas. I guess that I could replace the OS ROM on one of the emulators with my own OS? I think that some of the emulators have debug capability which might be the best way to go. Single step/trace would be ideal. I have rarely used any Atari emulator so have no idea which might be easiest/best. I also considered using an EPROM emulator in my 130XE which I know has a socketed ROM. There's no way of reaching the ROM with the emulator cable inside the 400/800 case. :-) I think that the full OS (even with hacking or adding RTS) is unlikely to work, but will make debugging more difficult. I intend to be using a 32 channel logic analyser to capture address, data, and control in order to determine what is and isn't working. I will take a look at the 5200 BIOS at it sounds like it might be easier to extract the code I require. For example in the 400/800 OS the display list is only setup when the OPEN command is executed and there is a lot os overhead which I don't need or want. --Atariry

I have just dusted off an old partially started project, my Atari (800) on a breadboard. I have breadboarded Sally, Antic and GTIA and used buffers to allow a FPGA to see the address and data busses. In the FPGA code I generate the "xtal" clock and emulate a 16k RAM and 8k ROM. In the future the idea is to add code to convert the output from the GTIA into HDMI. I am aware of Sophia(?), which I think does something similar, and from memory appears to use a CPLD rather than a FPGA. However I want to implement this myself and add sound over HDMI too. So, I need a binary to load into the 8k ROM. Since Pokey and PIA are missing, I do not want to use the normal Atari ROM. I would like to generate some simple code to initialise the chips and display a simple 40 x 24 line text screen. I have been looking through the Atari OS source code and I have tried to pick out pieces I need, but I haven't ever programmed the custom chips at this low level before. I have also googled (the web and this site) but not found anything helpful. I would simply like to ask if anyone is aware of some assembly source which does initialisation of the various chips from scratch and then possibly creates a display list and initialises ANTIC and GTIA? Perhaps part of a bigger project? Perhaps there are some other older threads in this part of the forum which someone might recall? Note: I don't normally visit this area - so my apologies in advance. Once the project moves forward I will post some pictures in the main 8-bit forum. regards... --Atariry

I am no expert, but I did make my own cart PCB (see my profile picture). The sockets are 24 pin which normally suggests a 4k ROM, however A12 is wired which suggests 8k ROMs. So this suggests that each socket is designed for a custom 8k ROM, making it a 16k cart as others have suggested. The two address range selects, notS4 and notS5 appear to go to either pin 20 or pin 21, so this must be the ROM not chip select input. The 2532 has pin 21 as chip select so I am guessing this, but you can buzz this out with a multimeter. Looking at A11 it connects to pin 18 which suggests a 2532 EPROM style pinout, which is not compatible with 2732 (4k) or the bigger pinout 2764 (8k). So appears to me to be a 8k custom ROM in a smaller 24 pin package, with not chip select on pin 20, A12 on pin 21, and A11 on pin 18. Obvious now I have googled the 2364 pinout. Hold on, I see that you have already figured out that the pinout is the rare(?) 2364, and tried an adapter. I think that if you use an adapter for a 2764 in each socket you should get the full 16k.