Looking for EPROM Part Number to use in IIgs with ROM-00.

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MarkO's picture
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Hello All;

I have been looking around for the last couple weeks for the EPROM equivalent of the Apple IIgs ROM-00/01.. My IIgs, which I just acquired from ebay has the ROM-00, a DIP with 28 pins:

WDC - Logo
651 VM E616
231024-1039
342-0077-A
c Apple 78, 81, 83, 86
c Microsoft 77

I have found reference to the 231024 PROM, but which EPROM is a Drop In replacement for it?

Where I work, we have devices that use the 27C512 EPROMS, which is a 28 Pin Device, but the 27C1024's are a 40 Pin Device.. I am kind of stuck..

Reactive Micro's Enhanced IIe Kit shows which EPROMs are used for the //e, but I have not located any such information for the IIgs..

I started using the Apple ][+ in JAN-1982, and bought a Half Share of an Apple ][e in NOV-1983. I am just getting back into working with the Apple ]['s again..

Thanks in advance...

MarkO

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speedyG's picture
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Re: Looking for EPROM Part Number to use in IIgs with ROM-00.

Hello Mark,
Apple IIgs vers. ROM1 content file - eprom no.: 342-0077-B eprom-typ: 27C1001
regards
speedyG

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MarkO's picture
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Re: Looking for EPROM Part Number to use in IIgs with ROM-00.

Thanks for the Reply...

I have access to some STMicroelectronics M27C1001-10F1, but they are 32 Pin devices.. We use the M27C1001-10F1 at work with a 128Kb Image, which would be the correct size for the Apple IIgs, but I think the Chip is too big for the Socket....

Is there maybe another variation of the 27C1001???

At work we use a Needham's EMP-10 ( like this one ) for Programming....

MarkO

speedyG's picture
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Re: Looking for EPROM Part Number to use in IIgs with ROM-00.

I´ll drop in back this evening and leave some links to the related topic - it will take some time to search my archive database ( size 55 GB ! ) with the technotes and feeds from all user groups.... i do remember that there had been some stuff issued to this topic.... as far as i remember it had something to do with the fact that the additional 2 pins each side on top of the socket had not been used ( i.e. 32pin solderpads but 28 pin socket.... ) the same topic was again unleashed with the release of the ROM 3 ... there where 2 different versions with 28pin and with 32pin PROMS....
but i do have to first search for that stuff....

but in fact the easiest way in past days that was common was to just swap the original ROMs ( from damaged ROM1 or by getting that ROM1 from the service... ) but i do remember also that there were different eproms availiable some with the standard pins OE, CE, WE, PV and some very rare had less pins that could be treated like Eprom at burning but had been sold in plastic DIP without "erase-windows" for UV and could only be programmed once like PROMs. That kind of EPROM-Replacement PROMs were also sold as cheaper alternatives to the common 2716, 2732, 27614 etc. and up to what I remember they came from japanese Factory (Hitachi or Toshiba)....

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Re: Looking for EPROM Part Number to use in IIgs with ROM-00.

There are a few pin swaps you can do with sandwiched sockets...

ReactiveMicro also sells them, but $25 is a bit extravagant in my opinion. Smile
http://www.reactivemicro.com/product_info.php?cPath=26&products_id=135

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MarkO's picture
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Re: Looking for EPROM Part Number to use in IIgs with ROM-00.

Fascinating....

Mostly Pin-Compatible, with a few "adjustments"..
M27C1001
I found a TC531000CP/CF document at a DataSheet archive..

Mostly Labor and Handling I would guess... The Sockets are of negligible cost..

Thank You very much for the Information...

speedyG's picture
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Re: Looking for EPROM Part Number to use in IIgs with ROM-00.

hello mark,
correct... i´ve made a page with the entire instructions ready for download at:
http://www.harrowalsh.de/Elektronik/APPLEBOX/iigsreplacementrom0.htm
its realy quite simple...
regards speedyG

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MarkO's picture
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Re: Looking for EPROM Part Number to use in IIgs with ROM-00.

That looks fantastic!!! Thanks for the Document....

Address Line A16 is obvious ( 2 --> 22 ), as well as Vcc ( 32 --> 28 ), but Pin 24 on the M27C1001 to Pin 20 on the TC531000 is not...

I need to go look at the Needham's EMP-10 EPROM Programmer, to see how to Read PROMS, in case I want to Clone and Modify anything.... Wink

speedyG's picture
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Re: Looking for EPROM Part Number to use in IIgs with ROM-00.

hello mark,
no need to read the proms.... the files are downloadable from internet....
http://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Computers/Apple%20II/Apple%20IIGS/ROM%20Images/

the pin 24 must be set to low level to enable output_enable from the eprom.....
the purpose is to connect output enable and chip enable ( both active while low ) to the chip_select at the socket and the chip_select from the board.

see explenation of the signals of the eprom in the table below.... that´s from the datasheet of the eprom !

but please bear in mind that at several IIGS-models with ROM 0 the VGC ( video graphic chip ) had some problems too and that in those models the VGC-chip needed replacement .... so probably it might be good idea to checkout that point too and to make sure that your IIGS is not one of those without swapped VGCchip and mistake in the VGCchip ! otherwise you might "proceed" from the "dungeons" ahead to "hell"...
see here for info:
http://www.reactivemicro.com/product_info.php?cPath=1_31&products_id=136

happy new year
speedyG

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Re: Looking for EPROM Part Number to use in IIgs with ROM-00.

I found a source for the Toshiba TC531000CP-12 1MB ROM IC's. It's a 28 pin DIP with 14mm width and the same pinouts as the orig.
Is there some reason nobody has tried this IC yet?

Since Reactive is closed right now, there is currently NO source for a pre-programmed ROM 01 for persons like myself other than purchasing a motherboard on ebay.

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Re: Looking for EPROM Part Number to use in IIgs with ROM-00.

Hello mkinn,
the reason for not using the 531000CP-12 is quite simple...
most of us, who play around with hardware have a simple epromburner as usually sold to public....
and usualy those burners are driven by parameter-data delivered with the specific burner-hardware...
and usualy those parameter lists contain the data for the 27xxx series - but not for the 53xxx series....
ROMs in most cases need other timing and other voltage for programming - so most of us like to keep on the safe side
and therefor use chips that are listed in the parameter-list....
sincerely
speedyG

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In early days I had a lot of money but no time - now I have no money but a lot of time....
the second part includes less friends but a lot more joy on life....