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Messages - BruceTanner

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Maintenance / Re: Enterprise 64 Video issue
« on: 2022.September.29. 22:54:09 »
PSU lists output as 9.5V 2A output. So how are they getting a 12V regulator to regulate?
It is a 1980s style DC-to-DC converter https://en.wikipedia.org/wiki/DC-to-DC_converter.

Other topics / Re: Allsorts of interesting finds
« on: 2022.May.15. 19:17:00 »
There was also a company called Elan in the 1980s that made eprom programmers. It was a popular name! :mrgreen:

For Sale / Re: Ebay auctions
« on: 2022.April.24. 00:29:59 »
The same seller will also happily sell you an empty Coca Cola bottle for £195! https://www.ebay.co.uk/itm/363300800022

Other topics / Re: Allsorts of interesting finds
« on: 2022.April.18. 15:32:28 »
So what is 2.2 and who did it?

Other topics / Re: Allsorts of interesting finds
« on: 2022.April.18. 13:15:49 »
:help BASIC is nicer in 2.2! Compare this 2.1 with your 2.2 above

The first of your changes is just the message length, 0043 instead of 003c. The second change is just the way it is printing the message - direct EXOS call instead of calling a subroutine!

Hardware / Re: Enterprise Deployment Attempt Over FPGA.
« on: 2022.March.16. 17:44:55 »
Still in the same point...
Just a thought... are you using a FPGA Z80? If you are, does the IN A,(C) instruction set the flags? The code I posted earlier relies on this but it is probably not the most frequently used Z80 feature!

Hardware / Re: Enterprise Deployment Attempt Over FPGA.
« on: 2022.March.16. 12:47:15 »
In the real hardware, each time i change unit (from A: to B:) the ep ask me to put a disk in the drive (there is a floppy in the drive) but the FPGA simply try to read the drive. Also, i only have one drive, but the fpga try to access inexistent drives. How it detect the drives?
It does a WD1770 "Restore" command, waits for the WD to become non-busy in the status resgister (bit 0 == 0), and then looks at bit 2 of the status register, which should be 0 if the drive head is now at track 0.

After testing drive A: in this way, it repeats for drive B:. For emulating a one-drive system, bit 2 of the status register needs to be 0 for drive A: and 1 for drive B:. after a "Restore" command.


Hardware / Re: Enterprise Deployment Attempt Over FPGA.
« on: 2022.March.14. 20:33:16 »
:shock: surely not! :lol: Thanks for fixing!

Hardware / Re: Enterprise Deployment Attempt Over FPGA.
« on: 2022.March.14. 18:37:05 »
I don't know what happened there, and sorry the tabs size is mixed up but hopefully it is usable. Ignore the bit at the end that says ". str_ireplace(' [ Attachment Invalid Or Does Not Exist ] '" I did not add that, the "system" did! :lol:


Hardware / Re: Enterprise Deployment Attempt Over FPGA.
« on: 2022.March.14. 18:33:27 »
In case it is any help, this is the loop within EXDOS that reads disk data:

Code: ZiLOG Z80 Assembler
  2. ;
  3. ;
  4. READ:   CALL    GET_CMD                 ;Get FDC command and timeout
  5.         OUT     (C),A                   ;Give command to FDC chip
  6.         SET     3,C                     ;Point to external status port 
  7. ;
  8. ; WAIT FOR FIRST DRQ WITH TIMEOUT.  138T (34.5us) per loop.
  9. ;
  10. RD_WT1: JR      $+2             ;13T    Padding
  11.         LD      A,0             ;8 T    Padding
  12.         IN      A,(C)           ;14T
  13.         JP      M,RD_LP         ;11T    Jump if got DRQ
  14.         DEC     DE              ;7 T    Decrement timeout count
  15.         IN      A,(C)           ;14T    Padding
  16.         IN      A,(C)           ;14T
  17.         JP      M,RD_LP         ;11T    Jump if got DRQ
  18.         LD      A,D             ;5 T   
  19.         OR      E               ;5 T
  20.         JP      Z,TIMED_OUT     ;11T    Jump if timeout expired
  21.         IN      A,(C)           ;14T
  22.         JP      P,RD_WT1        ;11T    Loop if still no DRQ   
  23. ;
  24. ;
  25. RD_LP:  DEC     C               ;5 T   
  26.         IN      A,(C)           ;14T    Get byte from FDC data register
  27.         LD      (HL),A          ;8+8T   Store it in RAM (clock stretch!)
  28.         INC     HL              ;7 T    Bump disk transfer address
  29.         INC     C               ;5 T
  30. RD_WT:  IN      A,(C)           ;14T   
  31.         AND     82H             ;8 T    Look at DRQ and INTRQ bits
  32.         JR      Z,RD_WT         ;8/13T  Wait if neither set
  33.         JP      M,RD_LP         ;11T    Jump if DRQ is set
  34. ;
  35.         JR      DONE_X          ;Exit when INTRQ occurs  
  38. GET_CMD:
  39. ;
  40. ;    Determine correct FDC command by including "settle delay" flag if
  41. ; required.  Also determine correct timeout delay for read and verify
  42. ; depending on "motor on" flag.  Write will ignore this value.
  43. ;
  44. ;
  45.         BIT     2,(IY+DELAY_FLAGS##)    ;Test "settle delay" flag
  46.         JR      Z,NO_SET
  47.         SET     2,A                     ;If required then set bit-2
  48. NO_SET:
  49. ;
  50.         LD      DE,09331h               ;Short timeout of 1.3s if motor on
  51.         BIT     7,(IY+DELAY_FLAGS##)
  52.         RET     NZ
  53.         LD      DE,0                    ;Long timeout of 2.3s if motor off
  54.         RET

Other topics / Re: Allsorts of interesting finds
« on: 2022.March.04. 23:24:21 »
:lol: :lol: :lol: I don't remember seeing that before!

Hall of Fame / Re: Your Computer Jan 1984 photo with names
« on: 2022.January.10. 11:19:10 »
I remember lots and lots of EPROM blowing and erasing! :lol:

We worked in a large room with the EP prototype in the middle of the room and our desks around the edge. We had to share the EP prototype. So there was no connection between our editing/assembling computers and the EP.

But in the early stages of development we also had a hacked version of ZSID the Z80 CP/M debugger working on the EP prototype.  It did character I/O through an extra hardware add-on to a terminal, either a parallel port or a serial UART I can't remember. But sorry I can't remember how we got the code into the EP memory. :(

Hall of Fame / Re: Your Computer Jan 1984 photo with names
« on: 2022.January.09. 21:46:27 »
I used a similar Apple setup before we got original IBM PCs. The z80 was on an expansion card inside the Apple, which allowed it to run CP/M. I remember using Wordstar a lot to create documents. Mine had the lid on with a monitor and disk drive on top. Using CP/M you could run Microsoft M80/L80 assembler/linker and so produce a z80 program that could be transfered to a "different" z80 system.

Hall of Fame / Re: Q&A with Bruce Tanner (IS-BASIC writer)
« on: 2022.January.09. 09:50:46 »
I do not have now the time-line of the Enterprise develeopement, maybe you can tell which stage of the develepment was decided to let the cursor move free on the screen? Did the CPC influenced this decision?

Anyway Did you try a CPC or other computer to get some inspiration for the developement?
No, EP development was happening while CPC development would have been happening, I think the cursor thing is a coincidence. In fact to this day I have never seen a CPC (but I've seen pictures, obviously). Don't forget the EP was originally intended to be released earlier than it eventually was, so was in development earlier. Amstrad would have seen early photos of the EP but they wouldn't have known about the cursor movement from that. I do wonder about the coloured keyboard keys though...

Hall of Fame / Re: Your Computer Jan 1984 photo with names
« on: 2022.January.08. 18:02:04 »
Hi Andy! Amazing after all these years... but I am most embarrassed that I didn't remember you when I wrote the names on tbe photo! But if you were around just for the holidays perhaps I can be excused... it was 39 years ago after all!

Do you remember that day? We had all been up all night and ambled down from Bedford Square to the Hippodrome at Leicester Square - a shambolic group as everyone can now see at this quite posh event. I recall having quite a job persuading the doorman to let us in!

Anyway hope you enjoy looking around the site - there have been some amazing and astonishing developments to the Enterprise!

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