ADFS 1.30 disassembly

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daveejhitchins
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Re: ADFS 1.30 disassembly

Post by daveejhitchins » Wed Aug 02, 2017 11:11 am

hoglet wrote:Now, just need a kind volunteer Plus3 owner to check the floppy driver part still works. Any takers?
Me - me - me :D

I've just built the first 'production' AP5 (yet to program the CPLD) so I'll do the testing with 1.03 fitted to the Acorn Plus 3 and test the floppy drives too.

More later . . .

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

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Re: ADFS 1.30 disassembly

Post by daveejhitchins » Sat Aug 05, 2017 10:58 am

OK . . . Just managed to test 1.03 in an Acorn Plus 3. Unfortunately it doesn't access the floppy drives. So it probably needs the addressing to the 1772 changing.

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
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Re: ADFS 1.30 disassembly

Post by hoglet » Sat Aug 05, 2017 11:04 am

daveejhitchins wrote:OK . . . Just managed to test 1.03 in an Acorn Plus 3. Unfortunately it doesn't access the floppy drives. So it probably needs the addressing to the 1772 changing.
It is currently using &FCC0-&FCC7. Is that not correct?

Does ELK100 work at all? (That's floppy + scsi)

Dave

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Re: ADFS 1.30 disassembly

Post by daveejhitchins » Sat Aug 05, 2017 11:07 am

hoglet wrote:
daveejhitchins wrote:OK . . . Just managed to test 1.03 in an Acorn Plus 3. Unfortunately it doesn't access the floppy drives. So it probably needs the addressing to the 1772 changing.
It is currently using &FCC0-&FCC7. Is that not correct?

Does ELK100 work at all? (That's floppy + scsi)

Dave
Sorry, just on my way out, so can't check . . . I'm assuming the addressing in incorrect as I get no drive light. I've had no further time to check. I may get a little time this evening, though. After that it'll be next Thursday, as I'm taking my Dad home to Portsmouth tomorrow.

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

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Re: ADFS 1.30 disassembly

Post by SimonSideburns » Sat Aug 05, 2017 10:07 pm

daveejhitchins wrote:I may get a little time this evening, though. After that it'll be next Thursday, as I'm taking my Dad home to Portsmouth tomorrow.

Dave H :D
My neck of the woods. I'm near Waterlooville just 'over the hill' from Portsmouth.
I'm writing a game where you can change your character from a Wizard to a monkey to a cat.

Well, Imogen that!

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Re: ADFS 1.30 disassembly

Post by hoglet » Thu Jul 19, 2018 1:14 pm

Hi all,

Mr Hitchens very kindly sent me an AP3/4, which means I can continue testing these ADFS builds..

As a reminder, the goal here was to create an Electron compatible version of ADFS:
- derived from Model B ADFS 1.30 (i.e. which has many bug fixes not in Electron ADFS 1.00)
- but with the floppy drivers from ADFS 1.00 (i.e. the Electron specific floppy drivers)

1. ELK100 = SCSI + Floppy

I've tested this with:
- SCSI (BeebSCSI) and Floppy
- SCSI only (BeebSCSI)
- Floppy only

As far as I can see, everything works very well.

2. ELK103 = IDE + Floppy

I've tested this with:
- IDE (DataCentre) and Floppy
- IDE only (DataCentre)
- Floppy only

Now, the first two combinations worked, but the flnal one (Floppy only) hangs.

A bit more tesing revealed:
- Floppy only (no AP5 present) works
- Floppy only (AP5 present) hangs

So what's going on?

It seems that the AP5 is changing the value read back from &FC4x, even if nothing is plugged in to the 1MHz bus
- No AP5 present, ?&FC4x = &FF
- AP5 present, ?&FC4x = &FE

Now the interesting bit. Here's the code in JHG's IDE Patch that detected the presence of the IDE controller:

Code: Select all

.L9A63
        LDX     LFC47
        INX
        BEQ     DriveNotPresent
        LDA     #$00
        RTS
.DriveNotPresent
        DEX
        RTS
This is saying if the value is &FF then nothing is present, anything else and it thinks the IDE controller is present. Hence the hang.

So why does the AP5 return &FE? It seems that's by design due to R7.
Selection_001.png
So, what's the purpose of R7??? It seems it was copied over from the original AP5 reverse engineered schematics (R1 there). It actually makes more sense for this to be on the Tube than the 1MHz bus. On the Tube it would ensure the Co Pro detection worked correctly.

Dave, is any chance this is a small error in the reverse engineering, and it's actually connected to the Tube D0?

Dave
Last edited by hoglet on Thu Jul 19, 2018 3:24 pm, edited 4 times in total.

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Re: ADFS 1.30 disassembly

Post by hoglet » Thu Jul 19, 2018 3:56 pm

I've just desoldered R7 and ELK103 no longer hangs (with the AP5 and the Floppy only)

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Re: ADFS 1.30 disassembly

Post by daveejhitchins » Sun Jul 22, 2018 7:13 am

hoglet wrote:
Thu Jul 19, 2018 1:14 pm
So, what's the purpose of R7??? It seems it was copied over from the original AP5 reverse engineered schematics (R1 there). It actually makes more sense for this to be on the Tube than the 1MHz bus. On the Tube it would ensure the Co Pro detection worked correctly.

Dave, is any chance this is a small error in the reverse engineering, and it's actually connected to the Tube D0?
I'll check this out, as soon as I've had breakfast . . .

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

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Re: ADFS 1.30 disassembly

Post by daveejhitchins » Sun Jul 22, 2018 9:19 am

OK, Can't find my original AP5 (I've put it somewhere safe :lol: ), however, here's a photo showing a resistor near to the Tube connector - I don't see any reason, other than the pull down in question, why that should be there! So, probably right about it being in the wrong place - - - I'll keep on searching for the actual AP5 then confirm when it's found.

Edit: So, if the resistor 'is' in the wrong place (?) how come the Tube code knows a 2CoPro isn't fitted?

Hmmm! Why can't I add add attachments all of a sudden? The Tab's there but doesn't work . . . . :twisted:

Dave H :?
Last edited by daveejhitchins on Sun Jul 22, 2018 9:34 am, edited 1 time in total.
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

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Re: ADFS 1.30 disassembly

Post by daveejhitchins » Sun Jul 22, 2018 10:20 am

Found it . . . There's a 1K pull down connected to pin 12 of the Tube connector - Data 0. With nothing connected to Data 0 on the 1MHz Bus connector. Ooooops!

It seems as if this may just need to be removed. I'll post this error in the AP5 thread and keep everyone up-to-date on any further issues with this.

While I was looking for the AP5 I found lots of other 'goodies' - Free + P&P - Keep a lookout in > for sale / freebies

Dave H :D

Edit: Added link to AP5 thread.
Last edited by daveejhitchins on Sun Jul 22, 2018 10:29 am, edited 1 time in total.
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

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