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1050 ROMs


tregare

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Looks like a timing margin improvement to me. The ideal timing for 19200 baud is 1000000/19200 = 52.1 cycles/bit, but the Atari sends a bit slower than that rate due to POKEY clock inaccuracy, so the ideal values are actually 52.5 cycles/bit for NTSC and 53.0 cycles/bit for PAL. Rev H's loop is 51 cycles/bit, so on average that's 1.5 cycles/bit error for NTSC and 2.0 cycles/bit for PAL. Any difference between the timing for this loop and the actual transmit rate is magnified because the skew error accumulates with each bit, so two cycles of error becomes a third of a bit cell by the stop bit. The additional cycles added in later revisions probably helped reduce receive errors for NTSC and especially PAL.

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Looks like a timing margin improvement to me. The ideal timing for 19200 baud is 1000000/19200 = 52.1 cycles/bit, but the Atari sends a bit slower than that rate due to POKEY clock inaccuracy, so the ideal values are actually 52.5 cycles/bit for NTSC and 53.0 cycles/bit for PAL. Rev H's loop is 51 cycles/bit, so on average that's 1.5 cycles/bit error for NTSC and 2.0 cycles/bit for PAL. Any difference between the timing for this loop and the actual transmit rate is magnified because the skew error accumulates with each bit, so two cycles of error becomes a third of a bit cell by the stop bit. The additional cycles added in later revisions probably helped reduce receive errors for NTSC and especially PAL.

Even better for this thought - just keep trying shit until it works :) Can't say I haven't done this with some software revisions. Not proud, but stuff happens.

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  • 3 weeks later...

 

I've been working on a tool to help reverse-engineer 6502 roms. It's a long way from being finished but it can produce a code/data segments report that can help with this sort of thing. Attached are reports for the J, K and L revisions. There's an attempt to identify each separate segment of code or data based on a few heuristics and then each one is fingerprinted to help identify code that's common to multiple sets. It also attempts to recognize "dark code" segments that may be unused or called by non-standard means.

 

Finished for the time being.

https://github.com/dhinson919/hac65

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I'm curious, is there a way to tell what Rev level your 1050 ROM is without opening up the drive?

And how can you tell the REV level by looking at a chip? I have a loose Tandon ROM chip that

has no Atari chip number on it or REV level that I can see. Markings on the chip:

 

94132B-2131

Tandon 1984

188063-001L

8447 CJA

 

Does this mean it's a rev J?

 

David

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  • 3 years later...
  • 1 year later...

I got the AM2732's in today but my programmer will only READ and BLANK check the chip. it fails to program it.

I had the same problem with the 2764's but I was able to program 27c64's

 

Any ideas what the problem might be? I have several chips and they all have the same issue.

 

Programmer is the TL866 II Plus.

 

image.thumb.png.6afd086d080fad559153f12bbc494fd7.png

 

image.thumb.jpeg.5c6c636eaa53211b4d13f7d10bef5df9.jpeg

Edited by sideburn
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there is a workaround on the TL866 when burning an ST 27C128. its not in the list so instead you select the AMD brand one (same pinout) and untick the "check ID" box. then the ST chips burns fine.

maybe something similar could help you out?

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Some AMD chips show the programming voltage explicitly in the top marks. The Tl866s depending on the version have different maximum programming voltage. So probably you are under the programming voltage with your EPROM programmer. To be sure you need the datasheet of the specific EPROM so you know it will work with your programmer before purchasing the eproms (except for most AMD eproms which you can get by reading the chip itself as I explained before).

Of course, I learned this the hard way.

 

 

Edited by manterola
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I forgot to mention that with some EPROM you can "inject" the necessary programming voltage by lifting the programming pin out of the tl866 and then connecting an external power supply to that pin and connecting the grounds together. However, it is a bit  convoluted procedure, also risky, because it is prone to errors,  and not always work.

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I'm afraid the TL866 II Plus won't do the job - the AM2732 needs 25V programming voltage, but max the TL866 II can supply is 18V. The original TL866 A/CS should work fine (it can do up to 25V) EDIT: scratch that, original TL866 only goes to 21V so won't work out of the box either

so long,

Hias

Edited by HiassofT
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2 hours ago, HiassofT said:

I'm afraid the TL866 II Plus won't do the job - the AM2732 needs 25V programming voltage, but max the TL866 II can supply is 18V. The original TL866 A/CS should work fine (it can do up to 25V) EDIT: scratch that, original TL866 only goes to 21V so won't work out of the box either

so long,

Hias

Bummer - I had the original, then upgraded to the plus.  Sucks it can't do the old stuff.

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1 hour ago, Stephen said:

Bummer - I had the original, then upgraded to the plus.  Sucks it can't do the old stuff.

If you do a web search there is a simple mod you can do that jacks the programming voltage up by 7 VDC for your unit. That means you need to select the voltage from the programming software (less 7 VDC) to get the right voltage for the EEPROM.

 

I did install the mod into my programmer (same as yours) but to be honest, never got it to work.

 

So I just resorted to ensuring I ALWAYs get the lower power EEPROMs to program (i.e. has "c" in middle of part number).

 

Edited by macsonny
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20 hours ago, HiassofT said:

I'm afraid the TL866 II Plus won't do the job - the AM2732 needs 25V programming voltage, but max the TL866 II can supply is 18V. The original TL866 A/CS should work fine (it can do up to 25V) EDIT: scratch that, original TL866 only goes to 21V so won't work out of the box either

so long,

Hias

But I can do a “C” type without issue always? 27C32 for example?

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Just check if your particular EPROM is in the device support list:

http://www.autoelectric.cn/MiniPro/TL866II_List.txt

 

There are tons of different manufacturers and the required algorithms to program the EPROM (or also flash, eeprom etc) may differ so double-check with the support list before buying any devices.

 

If it's not listed then, well, it may or may not work by choosing a similar device - it could also "seem to work" but the device looses it's memory after a (shorter or longer) while because the programming time was too short or the programming algorithm didn't match.

 

so long,

 

Hias

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