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Read 2716 UV EPROM

A little off topic, but the earliest versions of the 6800 had an undocumented instruction that actually caused gate latch-up when executed, and would burn-out the chip. Motorola obviously fixed that ASAP, but it's the first I heard of the HCF instruction - and probably the most appropriate case.
 
I would stop using the 5.5V supply to be honest, most old devices of this era are very specific / picky about what constitutes an acceptable supply voltage. If you get the same results using cleaning up + 5.0V supply, continue using 5.0V. It shouldn't be necessary to use more than that in read mode and there is an outside chance of damaging the original devices even with that very small amount of overvoltage - it's not really worth the risk.
 
here is another file saved as a bin, The chip is labeled 9BUG (so might be a monitor program for the 6909 ?) seems way too small though.
 

Attachments

  • 9BUG.zip
    216 bytes · Views: 3
SiriusHardware said:
I would stop using the 5.5V supply to be honest, most old devices of this era are very specific / picky about what constitutes an acceptable supply voltage. If you get the same results using cleaning up + 5.0V supply, continue using 5.0V. It shouldn't be necessary to use more than that in read mode and there is an outside chance of damaging the original devices even with that very small amount of overvoltage - it's not really worth the risk.
Click to expand...
its the only way the Mostek EPROM's will read anything intelligible with my XGecu T48 (TL866-3G)
The Intel D2716 chips are still giving me nothing but zeros even at 5.5V
Looks like I will need to find my Arduino

In a fit of impatience I put the GIMIX 6809 CPU card with the 4 intel ROMS in it onto the Backplane and powered it up. It did not catch fire, so I tried to measure the data and address lines with my Oscilloscope. There is activity, lots of pulsing so it's doing something...32439D5B-6275-4932-B8CF-1353B6011660.jpeg27D27C93-E438-4E6D-A8B4-F3BDB63ECCCD.jpeg
 
I'm wondering if the MOSTEK and Intel chips draw a lot of current from the 5V supply, a little bit more than your programmer is really capable of supplying, so you are having to 'turn up' the supply voltage to compensate for the voltage drop. If you are sufficiently curious try scoping the +5V supply pin of the EPROM before, during and after the READ process.

It should hold rock steady at 5.0V but if it slumps during the READ action, that's probably your problem.
 
fdiskitup said:
here is another file saved as a bin, The chip is labeled 9BUG (so might be a monitor program for the 6909 ?) seems way too small though.
Click to expand...
That one has even less in it.

Code: 
0000:   8613                    LDA     #$13                                                       
0002:   B7E780                  STA     $E780
0005:   8615                    LDA     #$15
0007:   B7E780                  STA     $E780
000A:   C639                    LDB     #$39
000C:   8602                    LDA     #$02
000E:   B5E780          L000E:  BITA    $E780
0011:   27FB                    BEQ     L000E
0013:   F7E781                  STB     $E781
0016:   20F6                    BRA     L000E

07FC:   F900                    FDB     $F900
07FE:   F800                    FDB     $F800
 
That bit of code is initialising (probably) an ACIA (or similar) and constantly output an ASCII '9' to the transmitter.

It is (possibly) a bit of test code.

Dave
 
daver2 said:
That bit of code is initialising (probably) an ACIA (or similar) and constantly output an ASCII '9' to the transmitter.

It is (possibly) a bit of test code.

Dave
Click to expand...
Sounds reasonable- the origin of these chips : they were supplied with the home brew 6809 system I’m restoring. The system came from a retired Motorola employee who was a chip designer for them from the 70s 80s 90s. The Chicago area Motorola co had an employee computer club that they encouraged to build with free Motorola chips.
The system has several prototype boards, floppy controller, dram board, parallel printer, wire wrap stuff, etc. I may never figure out what all the parts do, but it will be fun to try.
 
daver2 said:
That bit of code is initialising (probably) an ACIA (or similar) and constantly output an ASCII '9' to the transmitter.
Dave
Click to expand...
ACIA like this Motorola 6850,
44CD3DAC-4536-4ED5-8B89-E6172484512E.jpeg

Appears to be an asynchronous coms card ?
The empty sockets are for connections. (Not missing chips)
 
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fdiskitup said:
Specific part numbers are :
Intel D2716
MOSTEK MK2716J-8

I have been trying to read with my cheap XGecu model T48 (tried various 2716 chip types and manufacturers - nothing reproducible/verifiable).
The only other rom reading device I have is the XTIDE card.
Click to expand...
I don't own a XGecu model T48, But have you tried reading them as 28C16
 
Yes ! the Mostek Chips read fine as Atmel AT28C16 but not as 27C16 !
The intel Chips D2716 will read as 28C16 also

Here is something interesting finally: I think this is the equivalent of SWTBUG or MIKBUG;
 

Attachments

  • MICROBUG-P.A.Stark-AT28C16@DIP24.BIN.zip
    1.8 KB · Views: 10
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fdiskitup said:
Yes ! the Mostek Chips read fine as Atmel AT28C16 but not as 27C16 !
The intel Chips D2716 will read as 28C16 also

Here is something interesting finally: I think this is the equivalent of SWTBUG or MIKBUG;
Click to expand...
obligatory disassembly
 

Attachments

  • MICROBUG-P.A.Stark-AT28C16@DIP24.BIN.lst.zip
    7.4 KB · Views: 15
Thankyou for the disassembly work, I still didnt get my rasberry pi out to install your disassembler …
I’m hoping this rom will talk to the serial port on port 0 or 1. I didnt try it yet, instead I went down a rabbithole:
Further research into Peter A. Stark today - he wrote lots of good articles in Kilobaud magazine regarding the SWTPc (p58 march 1979). Available on archive.org.
 
I've also noticed that my Intel 2716 do not read correctly with the T48. NEC and ST work fine. Data sheet says 150mA so not sure why the 350mA setting doesn't cover it. Maybe the programmer needs to slow down.
 
I've been pointed here - I have the same problem with an Intel 2716 '77 trying to read it with my Stag PP39. I ended up dumping the memory on the PET to a file and checking it on my PC (via a PET Disk Max 2.0). The Stag would read it consistently but it was rubbish.

I'll try my Arduino based reader in a week or so to see what happens then.

EPROM questions - UK Vintage Radio Repair and Restoration Discussion Forum

EPROM questions Vintage Computers
www.vintage-radio.net

Colin.
 
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