Fitting a Minerva EEPROM to a Issue 5 QL

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Pr0f
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Re: Fitting a Minerva EEPROM to a Issue 5 QL

Postby Pr0f » Thu Mar 12, 2020 10:30 am

In theory it should be possible to do that with 5V writeable flash, but there is a command sequence to programming these FLASH chips that has to be followed, along with a much more extended write time - the 29f040 chip actually buffers a whole block to write, and you can come back and interrogate the chip by reading / writing certain locations to check when that is done - the program would have to be running from some other memory rather than the ROM - the chip that is used in Tetroids ROM switcher is only partly exposed to the QL address bus - in blocks of 64K - that's why he has the adaptor board for programming up the whole chip.


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Re: Fitting a Minerva EEPROM to a Issue 5 QL

Postby dilwyn » Thu Mar 12, 2020 12:06 pm

Derek_Stewart wrote:I remember in the 1990s some one in the Newcastle QL group had board in his QL, which he could change the ROM image with a manual read/write switch. Pity I did not get one.

There was also the MCS Multi-ROM [url]https://qlwiki.qlforum.co.uk/doku.php?id=qlwiki:mcs_multirom&s[]=mcs[/url] which plugged into the back EPROM slot, which contained its own 16K RAM to allow 16K ROM images to be uploaded. Not quite the same thing, I know, but still a useful little device which didn't really get the attentinit deserves. Wonder if this kind of device could be developed into a 48K or 64K external flash memory to allow a QL ROM image to be uploaded and restart with that image as the operating system?


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Re: Fitting a Minerva EEPROM to a Issue 5 QL

Postby Vyper68 » Thu Mar 12, 2020 4:08 pm

Well I went and did something a bit rash ( not like me, I know ) There were a couple of QLROM EPROM adapter PCB's offered in other similar threads on here. One uses a 74LS00 and has a decoupling capacitor and the other a 74HCT00 and no decoupling. There were .brd & .sch files for each and I was able to produce some Gerbers from them. I went and ordered 5 of each as the min qty was 5 in Black. The plan is to build one for myself and use one of the batch of Winbond 27c512 EEPROMs I have here. I only really want to change to Minerva so one of my EEPROMs should do the trick. The rest will be FOC to anyone who would like one if that's OK with everyone.

I prefer making my own little bits like this but Tetroid's kit does look really nice so I plan to start saving for a Gold Card clone once this month is out the way.


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Re: Fitting a Minerva EEPROM to a Issue 5 QL

Postby martyn_hill » Thu Mar 12, 2020 4:50 pm

Sounds like a sensible plan, Vyper68!


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Re: Fitting a Minerva EEPROM to a Issue 5 QL

Postby Vyper68 » Wed Apr 01, 2020 2:11 pm

I have fitted a 27c512 EEPROM with Minerva 1.98 and it works and boots Minerva up. I did combine the Minerva with Toolkit 2 and padded the Minerva ROM so the Toolkit starts at $C000 but typing “tk2_ex” just gives a bad name so I must have made a mistake somewhere. The internal ROM board set the jumper for Internal rather than external as I thought the latter meant the ROM expansion port.
Any pointers are welcome.


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dex
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Re: Fitting a Minerva EEPROM to a Issue 5 QL

Postby dex » Wed Apr 01, 2020 2:16 pm

Vyper68 wrote:typing “tk2_ex” just gives a bad name

Yes.
The proper command is TK2_EXT.


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Re: Fitting a Minerva EEPROM to a Issue 5 QL

Postby Derek_Stewart » Wed Apr 01, 2020 3:16 pm

Hi,

Does the Toolkit II rom message appear on the Minerva start screen?


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Re: Fitting a Minerva EEPROM to a Issue 5 QL

Postby Vyper68 » Wed Apr 01, 2020 3:47 pm

dex wrote:
Vyper68 wrote:typing “tk2_ex” just gives a bad name

Yes.
The proper command is TK2_EXT.


Still gives “bad name” response sadly.


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Re: Fitting a Minerva EEPROM to a Issue 5 QL

Postby Vyper68 » Wed Apr 01, 2020 5:00 pm

Derek_Stewart wrote:Hi,

Does the Toolkit II rom message appear on the Minerva start screen?

No it doesn’t show up, just my Kempston disk Interface. Did I set the EEPROM up incorrectly I just did a binary concantation with Minerva and TK232 using Windows command line to create a 64K binary file and burned that. So TK2 started at $C000 and Minerva was $0000 - $BFFF. I am assuming I needed to have a Jumper on the 3 pin header so it is bridging the side marked INT on the PCB.


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Re: Fitting a Minerva EEPROM to a Issue 5 QL

Postby dilwyn » Wed Apr 01, 2020 5:54 pm

Also depends on what TK2 image it was. Some of the 16K plug in EPROMs didn't have a TK2_EXT command (although most did, to enforce the TK2 definitions if required later). The extensions in those versions were just linked in at startup and that was that available to use without any action on your part. Try using one of the TK2 extensions, if it works, youll know that was the case. TBH, very unlikely, but one of those quick things to test before wasting time on something which takes much longer. If this was the case, you'd see a startup message top of the screen before pressing F1/F2 to start the QL.


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