QL Add-on ROM

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tcat
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QL Add-on ROM

Postby tcat » Mon Mar 23, 2020 9:24 am

Hi,

Seeing QL h/w memory map, I wonder how to make use of the add-on rom address space $fffff-$e0000, on a real machine?

memory.png
QL memory map
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Tomas


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Pr0f
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Re: QL Add-on ROM

Postby Pr0f » Mon Mar 23, 2020 9:55 am

The ROM space would need to be accessed by the expansion connector - and the memory map is a bit misleading too

Minerva ROM will scan the various places that ROM can exist - so that will find any ROM's you have there, older ROM versions tend to only scan for the first peripheral rom at 0c0000, and not any higher addresses.

Some documentation shows the space between 0c0000 and 0fffff as one block divided into 16 x 16K spaces, others show the layout you have. The first layout seems to be how hardware cards - like Qubide for instance, use the space.


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Re: QL Add-on ROM

Postby tcat » Mon Mar 23, 2020 10:51 am

Hi,

The map I took from `The QL Technical guide', I thought a definitive reference at least for older QL ROMs, prior Minerva and SMSQ.

I was curious what sort of ROMs were available back in the days, compared to what we can do today, e.g. QuibIDE.

I was thinking of using some flash EEPROM, and map it to the address space from either $C0000 or $E0000.

Expansion slot is on my QL already occupied by 512K `Simple RAM', with no through port.

I wonder where best physically place such DIY board, does external plugin ROM socket expose enough address lines?

Many thanks
Tomas


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Pr0f
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Re: QL Add-on ROM

Postby Pr0f » Mon Mar 23, 2020 1:03 pm

A backplane - like the one tetroid sells will get around your used expansion port.

In theory you could put your eproms at either location. To be linked into the system, they would need ROM header and some code to activate the contents. Ideal for things like toolkits. Not sure if there is a 'ROM' Drive equivalent that would let you access them as a read only file system?


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Re: QL Add-on ROM

Postby tcat » Mon Mar 23, 2020 4:27 pm

Hi,

EDIT
Looking at ROM extension port, it provides some [all] address, data lines, and ROMOE.

romport.png
ROM cartridge slot
romport.png (44.81 KiB) Viewed 722 times

It would be nice to see the extended environment on standard QL system, so I was hoping to put, TKII, PE, QPAC, RAMPRT and SerMouse on the flash EEPROM, but I am not quite sure if they are all romable?

As there is only ROMOE, I cannot see a way to program the flash right from the QL, or is there?

Currently I boot extended environment over serial line, it takes few minutes to complete. Could be done from microdrive a bit faster though.

Tomas
Last edited by tcat on Mon Mar 23, 2020 4:34 pm, edited 1 time in total.


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Pr0f
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Re: QL Add-on ROM

Postby Pr0f » Mon Mar 23, 2020 4:31 pm

The ROMOEH signal (active high) is only active for the lowest 64K address space and the Address lines only cover this too - A0-A15, so no decoding for ROM's at higher addresses


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Re: QL Add-on ROM

Postby tcat » Mon Mar 23, 2020 5:04 pm

Hi,

I see, now to avoid internal expansion port, what other option we could have. A daughter board piggy backing over ROM chips?

Tomas


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Re: QL Add-on ROM

Postby tcat » Wed Mar 25, 2020 8:17 am

Hi,

Some statistics on versions I use on my QL.

Code: Select all

16K   TKII
16K   PTR_GEN
12K   HOT_REXT
12K   WMAN
40K   qpac2
8.0K   ramprt
4.0K   SERMouse
108K   total

Provided QPAC is or can be made romable easily. This may fit $E0000-$FFFFF which is 128K.

I was hoping to use either eeprom AM29F010 (128K, 8x16K sectors) or AM29F040(512K, 8x64K sectors). The latter seems still available. Cannot tell how fast these chips are compared to QL ROM.

I believe that the code can be executed from EEPROM, rather than copied to RAM, after it is linked into the system during boot.

Tomas


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Re: QL Add-on ROM

Postby RalfR » Wed Mar 25, 2020 8:29 am

tcat wrote:Hi,

Some statistics on versions I use on my QL.

Code: Select all

16K   TKII
16K   PTR_GEN
12K   HOT_REXT
12K   WMAN
40K   qpac2
8.0K   ramprt
4.0K   SERMouse
108K   total

Provided QPAC is or can be made romable easily. This may fit $E0000-$FFFFF which is 128K.


With the exception of "sermouse", which I never used (so I can`t say, if it is ROMable), I can say that all the above mentioned are ROMable. I once had a QFlash card with three EPROMs in my QL and I have used this stuff. Software from TT is always ROMable.


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Re: QL Add-on ROM

Postby Pr0f » Wed Mar 25, 2020 8:32 am

I have bought a few 29F040 Flash chips recently - most are either 120ns or 90s, you can get faster but you don't need them and they cost more. Either of the above should be quick enough for QL use



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