warerat

I've always wondered why people say this, but... every 800 I've had has *ok* video output. I'd even venture to say it's different from all the others because the white letters are fringed with purple (yes, my color delay pot is adjusted properly) and it definitely doesn't look better than a Supervideo upgraded XE. I'm saying this because I've only used the composite out. Is the implication that the separate chroma/luma outputs instead of composite will make my eyes pop out of my skull?

Card 1 is a 32K RAM card, so it goes in slot 2 and you yank out any memory from slot 3. This is what you used to keep a 48K config with the Bit3 or Austin-Franklin dedicated 80-column cards. Like James says, card 2 is the CPU card with the regular 6502. With a CTIA, to boot.

Oops, didn't attach the pictures...

Prototype I did for 64K Atari 800 OS board with RAM under ROM-- this was the proof of concept and how it all got started. I made a few of these for some members on this forum. This one I want to say is probably from around January 2006. Three chips (16K EPROM, 32K SRAM, GAL16V8) and about 20 blue-wire connections. That coiled wire connects to PORTB bit 0. In theory you can use the unused pin connection on the OS module (pin 20, third pin on bottom right) and then jumper the slot on the motherboard to PIA bit 0 if you wanted a clean install. The OS on this one was obviously slightly modified to have the reset NMI handler. No switchable BASIC or Self-test available. Bare bones 800XL compatibility. Kind of a kludge, but it worked. Not really 100% compatible but close enough to run most disk-based apps.

Another cart to try is Star Raiders as it also looks like a diagnostic cart to the OS. Don't think the OS ROM is your problem. You can try replacing those two ICs but if you're getting the game to come up like that, I doubt they're the culprits. Trying plugging in one memory module at a time and power on. While not impossible, it's highly unlikely all three 16K modules are bad (I assume you have 48K). You could also have a bad PIA.

Where is the power board vent? Tempest Towards the rear right.

Only vent you really care about on the 800 is above the power board, the vents on the other side are just cooling off empty space. You'd figure they would add vents to the metal cage where all the memory cards are but it's not the case.

Well the 400 obviously doesn't have an OS board. If you look to the lower left of the cart slot on the 400 motherboard you'll see three IC's with the same part numbers as A401-A403 on the 800 OS board. These are the ROMs. Two are 4K and the floating point is 2K. Just exchange the ones with the same part numbers (COXXXXX).

The ROMs from your 400 motherboard will work in the 800 OS board.

Nice work!

Well this is a WIP, and have only been able to spend a little bit of time on it-- so it progresses slowly when it does like most hobby projects. I re-did the design and at this point I have essentially an all-in-one board that can switch back and forth between different three different 800 memory maps (stock 48K, stock 52K, Axlon 512K) and four XE memory maps (stock 128K, 320K, two different 576K). I've had to physically re-work the prototype to allow a larger CPLD to allow for this extra functionality. The point is, it can be done. While the hardware is essentially the same, there are some aspects with the design of the 800 that warrant some extra attention. The simplest option to turn it into a 64K 800XL is to equip your OS board (I've done this in the past and was part of the initial proof-of-concept) with an additional 16K of memory and put the XL OS in ROM with a connection to PIA bit 0. That would provide the minimum compatibility, but you'd still have work to do on the reset circuit, cartridge interlock, and fix a pin on the cart slot (the 800 doesn't supply the phase 2 clock to the cart slot, only RAS). I don't know what level of experience you have soldering or what equipment you have, but it can get rather involved.

Out of curiosity, are the two green Auto Term LEDs lit on the back on the enclosure?

Termination has to do with the signal quality. If the drive is marginally terminated, it may or may not work (if the cable is really short then your chances increase that it will work). Termination affects not only the signal quality but also the delay and settle time of the signals. When the drive selection occurs (asserting SEL- and negated target ID on the bus) there's a delay between the time the target ID sees the select request from the host (MIO) and a delay between the drive asserts its acknowledgement. The termination (or lack of) can affect those times and affect how quickly the drive responds. SCSI parity is practically useless on the Atari (BB or MIO) because neither the hardware or software is providing a mechanism to recover or detect a parity error. The only practical use is to allow a newer parity-only drive to be used. If you're familiar with all these 'LS280 hacks, all they are doing is sending the parity bit to the drive. If the drive hardware really did detect an error, it lets the host know through a message mechanism that neither the BB or MIO implement in hardware. Remember, these are minimal interfaces to SCSI. Termination is always a factor-- it is part of the physical design of the SCSI bus. If your signal path is bad, parity or non-parity, it's not going to work as expected. Termination isn't optional. Parity is.

Carmel "Energizer" Andrews. Keeps going, and going, and going....

in keeping with the spirit of the thread if mem recalls I no how to spll (i.e. spelling I know how to)

Depends on the CPU board revision you have. If it's CO15500 it takes the same SALLY 6502C as the XL/XE. That rev has a single 74LS244 on board. I bought a whole lot of 800s and only a couple had that kind of CPU board. I can only speak for NTSC machines. Otherwise, assuming the CPU in the picture is the same, I have used that Synertek 6502A in the older-rev CPU board with no problems as they take stock 6502 chips.

About damn time. I am amused by your "thought" process. Even though you get this reaction over and over and over from complete strangers, you still feign innocence. Pulbic or pubic? Of course not, because most of us are used to you and ignore you anyway. You're harmless. Carmel, don't. Just stop right now. You and I are on completely different levels-- and while you're not the sharpest tool in the shed, you know what I mean on that. If I thought any constructive rebuttal against you would do any good, I'd really let you have it. But I'd have a better chance telling my five year-old nephew to behave. But seriously man, don't. You can waffle and try to turn things around all you want, but the fact is it is *you* that brings this on yourself. I know that is hard to accept and is confusing to you. This isn't your first rodeo and this happens to you all the time here (and I'm sure in the real world) and when it does you always put on the raped virgin act as if we're the bad people against you. Your use of the word credible is offensive, because you are anything but that. Denial is a very powerful force. P.S. You'll look more dignified defending yourself using spelling and punctuation correctly instead of typing with your feet. Take your blue pill, drink your milk, and eat your cookies. Dinner will be ready soon.

There was a substantial effort from Atari in '82 in a revolutionary new memory interface chipset called CARMELIA (Computer Assisted Read-Memory Logic Interface Adapter) in the hopes in increasing the efficiency of reading memory (CARMEL for short). At the time R&D (through a government-sponsored black-box project) was trying to determine if different read/write algorithms to semiconductor memory could be attributed to how humans recalled information. In the case of this chipset, it failed miserably. Some of the problems the engineers found was while writes to memory seemingly worked (i.e. providing correct/factual information to store into memory) the reads would produce jumbled and incoherent/improbable results that could not be reproduced consistently, not matter how hard they tried to correct them. Theorists believe that the CARMEL chipset could indeed possess the power to correctly store information, but it was determined that due to major flaws within the core logic, that it would be impossible or impractical to market the chipset because of the grave errors in the recall circuit. Computer memory devices based around this chipset showed random behavior-- a casual or inexperienced observer would think the reconstitution of facts from memory was logical and concise, but upon closer examination it was shown the recall capability was completely jumbled and incoherent more often than not producing amusing, but incorrect results. From here, Atari moved on to more serious projects like the pre-cursor for the Amiga chipset.

Why bother when technobabble mad libs is so much fun? Kind of like how Commodore reverse-engineered the VCS to make the VIC-20? I'm speechless. And strangely enough, grinning ear-to-ear at the same time.

Why bother when technobabble mad libs is so much fun? Kind of like how Commodore reverse-engineered the VCS to make the VIC-20?

I'll take one NTSC VBXE.

I just coil the cord up and tie wrap it inside, assuming you don't want it anymore. There's lots of room for it inside the case on the left side. Then that way you don't lose the cable.

You can't see it from the picture but my adapter is a Datamate SP5000-5068-13 I pulled off some old Compaq gear. It isn't just a converter-- it has resistor networks inside that terminate the high byte. I'm not saying this is the one you need to use, it's just one of many that does what needs to be done. The whole concept of high-byte termination is so when you connect a 16-bit device to an 8-bit bus, the upper data bus won't float and pick up noise. Termination in this case means the upper byte of the data bus and its parity line is tied high. I'm pretty sure I already posted a link about this. See here: http://www.scsita.org/aboutscsi/SCSI_Termi...Tutorial.html#4 You really need to refer to this document. It explains all the caveats of connecting different types of devices, specifically sections 4 and 6 are relevant to connecting newer devices to the MIO. Nope, regular cable.

Sounds like thermal recal. The Cheetah I'm using does it in a pattern every so often, when idle. Tick-tick---tick-tick--tick. Completely harmless, normal, and common in drives made in the mid-late 90's.

Yup.