ST SHIFTER operation ?

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exxos
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Re: ST SHIFTER operation ?

Post by exxos » Wed Nov 01, 2017 10:01 pm

keli wrote:
Wed Nov 01, 2017 11:43 am
Without checking, I'm afraid that the GLUE will only activate /CS for the first 17 of the 32 available addresses. If you try accessing the registers at 0xFF8262-0xFF826E frome code on an STF, do you get a bus error or will the /CS pin on the Shifter be pulled low?
17 is all I need, palette registers and control register. I was just saying the address space is 32 long, even though the shifter won't use them all.

Of course different on the TT, would need its 256 palette registers there, and need a bunch of address decoding etc..
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Smonson
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Re: ST SHIFTER operation ?

Post by Smonson » Wed Nov 01, 2017 11:36 pm

keli wrote:
Wed Nov 01, 2017 11:43 am
Without checking, I'm afraid that the GLUE will only activate /CS for the first 17 of the 32 available addresses. If you try accessing the registers at 0xFF8262-0xFF826E frome code on an STF, do you get a bus error or will the /CS pin on the Shifter be pulled low?
If that's the case, a simple way around it is to use register 0 for palette index and register 1 for the register itself, instead of colour 0 and 1, when in 256-colour mode.

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Re: ST SHIFTER operation ?

Post by exxos » Thu Nov 02, 2017 10:36 am

Small circuit update.. The registers select blocks now wired up..

I think the only thing which is not added so for, is the control register.. Currently everything on this circuit is wired for low resolution. Once the control register is added, the other resolutions will then be supported. Though I am not adding anything else this circuit now until the basic low resolution designs tested. Otherwise circuit is just going to be too complicated to debug if I add other things at this stage.
shifter_copy.jpg
shifter_copy.jpg (5.84 MiB) Viewed 494 times

EDIT:

A few typo fixes later..
Capture.JPG
Capture.JPG (32.14 KiB) Viewed 491 times

EDIT2:
I updated the 373 latches into a single block file, basically together 16 bit version. While I was messing about, I remove the tri-state outputs these latches, thinking it would reduce the logic count. But it seems it did not make any difference and the logic out as exactly as before.

So either my test wasn't good enough, or the compiler is actually really good in optimising circuits.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: ST SHIFTER operation ?

Post by exxos » Thu Nov 02, 2017 9:41 pm

shifter_copy.jpg
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Added in the control register. It does not do actual functions yet, but the register should at least be readable and writable to.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
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Smonson
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Re: ST SHIFTER operation ?

Post by Smonson » Tue Nov 14, 2017 12:32 pm

keli wrote:
Wed Nov 01, 2017 11:43 am
Without checking, I'm afraid that the GLUE will only activate /CS for the first 17 of the 32 available addresses. If you try accessing the registers at 0xFF8262-0xFF826E frome code on an STF, do you get a bus error or will the /CS pin on the Shifter be pulled low?
I tested this tonight by adding extra registers in my FPGA-shifter, and they can be written and read back OK at all 32 addresses.

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