STFM (2 ROM): What EEPROM chips are compatible?

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stephen_usher
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STFM (2 ROM): What EEPROM chips are compatible?

Post by stephen_usher »

I've been searching on-line this morning and can't seem to get a straight answer to the question:

What EEPROM models are pin compatible with the sockets on a STFM (2 ROM) motherboard?

(Background: I need to make a pair of DiagROM-ST ROMs.)
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
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JezC
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Re: STFM (2 ROM): What EEPROM chips are compatible?

Post by JezC »

Not quite the answer to your question...but the TF DiagROM image will fit in a pair of 27512 EPROMS.

There are a few Microchip OTP EPROMS in 28 pin packages - Farnell has a few for example, including 512kbit.
So, if the pinout matches, they might be an option.
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Re: STFM (2 ROM): What EEPROM chips are compatible?

Post by exxos »

2 ROM's nope, none. Only 32pin EPROMS which you have to bodge fit.

EDIT:
This is why I sell dualtos boards. Some others on here have some EPROM adapters which should fit more layouts. I think it was @DoG who did some.
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Re: STFM (2 ROM): What EEPROM chips are compatible?

Post by rubber_jonnie »

TBH I have a pile of 27C256s and just fit an extra 4 sockets :)

Otherwise I use exxos' DualTOS adapters.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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JezC
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Re: STFM (2 ROM): What EEPROM chips are compatible?

Post by JezC »

rubber_jonnie wrote: Fri Sep 25, 2020 11:01 am TBH I have a pile of 27C512s and just fit an extra 4 sockets :)

Otherwise I use exxos' DualTOS adapters.
Don't you only need 6x 27C256 for 6 ROMs? That gives you all 192k of ROM decode space...

Anyway...if TF's build of DiagROM is good enough that will just for into 2x 27C512 (after you trim off the 'junk' at the end of each image)
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Re: STFM (2 ROM): What EEPROM chips are compatible?

Post by rubber_jonnie »

JezC wrote: Fri Sep 25, 2020 11:10 am
rubber_jonnie wrote: Fri Sep 25, 2020 11:01 am TBH I have a pile of 27C512s and just fit an extra 4 sockets :)

Otherwise I use exxos' DualTOS adapters.
Don't you only need 6x 27C256 for 6 ROMs? That gives you all 192k of ROM decode space...
Indeed, I meant to write 27C256 and wrote 27C512 because my brain is addled at the moment! D' oh

Corrected!
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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stephen_usher
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Re: STFM (2 ROM): What EEPROM chips are compatible?

Post by stephen_usher »

Oh bother! Oh well. No DiagROM for me this weekend then.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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JezC
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Re: STFM (2 ROM): What EEPROM chips are compatible?

Post by JezC »

rubber_jonnie wrote: Fri Sep 25, 2020 11:27 am Indeed, I meant to write 27C256 and wrote 27C512 because my brain is addled at the moment! D' oh
Know that feeling all too well :lol: especially when our kitten decides to have a mad half hour at 2:30 AM!
zzzzzzzzzzz...sorry, must have dozed off there :roll:
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Re: STFM (2 ROM): What EEPROM chips are compatible?

Post by rubber_jonnie »

JezC wrote: Fri Sep 25, 2020 12:18 pm
rubber_jonnie wrote: Fri Sep 25, 2020 11:27 am Indeed, I meant to write 27C256 and wrote 27C512 because my brain is addled at the moment! D' oh
Know that feeling all too well :lol: especially when our kitten decides to have a mad half hour at 2:30 AM!
zzzzzzzzzzz...sorry, must have dozed off there :roll:
I feel ya, except our kitten is a 6 year old cat......
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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Re: STFM (2 ROM): What EEPROM chips are compatible?

Post by DoG »

If you got 2 ROM board you should be able to move 3 solderblobs and use 6 27C256 instead. Just split DIAGROM into 6 pieces. Otherwise you can use 2 32pin 27C010 and some wire to mod the 2 EPROMs to use DIAGROM on that. You don't need a pcb mod board but it for sure will be neater. I made some and I wrote it in my blog a while ago. Works as a normal 28-32 pin adapter (with ROM switch for 4 ROMs and external chip enable/select signal for decoder board).

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