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#107836 - 11/06/16 06:16 PM Re: Requirements? [Re: Edstrom]
Al Kossow Offline
Senior Member

Registered: 01/06/11
Posts: 144
Originally Posted By Edstrom
Like the Mac SE Nubus slot


The SE had a processor direct slot which wasn't Nubus

SE/30 had a pseudo slot for video, and a PDS. Neither were Nubus

SI/CI had a PDS that could take a nubus adapter (basically the nubus interface chips from the Mac II on a card)

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#107837 - 11/06/16 07:08 PM Re: Requirements? [Re: rfka01]
Edstrom Offline
Senior Member

Registered: 08/11/15
Posts: 294
Thx Al, I have an SE and always thought it was a Nubus slot. smile
_________________________
https://frakaday.blogspot.se/

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#107949 - 11/20/16 04:03 PM Re: Requirements? [Re: crazyc]
Bavarese Offline
Senior Member

Registered: 04/29/12
Posts: 140
Loc: Germany
Originally Posted By crazyc
(...) I was just laying out the docs for why RDAT is like it is. It might be that the bytes are supposed to be cleared, set or complemented as they are read out but nothing says that anywhere.


Whenever DBIN is asserted on the 7220, a RMW cycle (memory access) takes place (display cycles are entirely seperate). Reading also means writing or updating & refreshing the memory (to "simplify external glue logic").

I assume RDAT works the same way as WDAT does - at least parameters look exactly the same for both (p.215 and 216 of the Rainbow Graphics Option Manual)

An external logic (named "Combiner" in Tony Duell's schematics (page 10) kicks in whenever the GDC's WRITE_MASK is set to all ones
Reference

It appears there are yet no hooks to change the bit mask before an update.

As i am no hardware guy, i have now disassembled most of the Graphcis Diagnostic Disk with IDA Free (and hope it clears things up) smile


Some unresolved questions keep bugging me:
- what does the Graphics MMU actually do (see schematics)...?

- the Graphics Option Manual from DEC talks about "synchronization of RMW cycles" (when writing to the special port 50).

Assumption: this simply sets the external WRITE_MASK to FFFF and sets the external ALU (a PAL16L8) to zero (for replace).

Comments are welcome.

P.S.: i have aquired (somewhat rare) German docs for the GDR clone of the NEC 7220 (U82720). Is Bitsavers interested in foreign language manuals?


Edited by Bavarese (11/20/16 05:20 PM)

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#107954 - 11/20/16 10:40 PM Re: Requirements? [Re: rfka01]
shattered Offline
Senior Member

Registered: 05/30/12
Posts: 366
Is it an exact clone? A few Robotron machines use it (A7150 in particular).

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#107957 - 11/21/16 01:18 PM Re: Requirements? [Re: rfka01]
Bavarese Offline
Senior Member

Registered: 04/29/12
Posts: 140
Loc: Germany
I can tell for sure it is pin-compatible and likely was "redesigned by looking at horizontal and vertical microsections / micrographs" (a standard technique employed in the GDR and mastered to perfection). (no first hand info, quote from related Robotron pages)

Known versions:
- U82720 DC04 (8,34 Mhz @ VIS3)
- less than 4 MHz clock: U82720 DC03 and DC02

U82720 veb mikroelektronik / Robotron (198x)
U82720 from Robotron (PDF in question)

Raw TIFs suited for OCR

VIS3 graphics card (GDR 19??)
VIS3 Beschreibung und Treiber (DOC)

The VIS3 package (above) contains lots of drivers and good documentation. Even the 4 plane mode (known from the Rainbow) is described...


Edited by Bavarese (11/21/16 03:23 PM)

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#107958 - 11/21/16 05:42 PM Re: Requirements? [Re: rfka01]
crazyc Offline
Senior Member

Registered: 01/22/12
Posts: 629



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#108127 - 12/05/16 03:51 PM Re: Requirements? [Re: rfka01]
Bavarese Offline
Senior Member

Registered: 04/29/12
Posts: 140
Loc: Germany
Thanks, Crazyc smile

First, there is a new version of the GDC diag disassembly.

A new pull request tries to address reentrance problems (after reset) and makes vertical scroll fully functional.

This lets you dive deeper into the reactor core in SCRAM and - more important - fixes the LIST command in DEC's version of GWBASIC (which was next to unusable)

Games that work well are MMIND (MasterMind), PACMAN, SCRAM, and GOTELO (Othello).

Programs with initialization / redraw / reentrance problems (invocation order matters, at least in emulation):
- CANON (high resolution + vectors),
- Solitaire (SOLIT.EXE) and
- GDEMO (from GRPHCS.ARC, interactive graphics interpreter from Livermore Labs 1985),
- plus the Monitor Aligment Test (from the GDC test disk).

There are some interesting cursor issues left. It all depends on the application (REGIS, GSX, GW-BASIC). In the 1st screenshot, the cursor block is invisible and leaves a one line trail behind). The 2nd one shows a scenario where cursor doesn't clear properly (high resolution game with REGIS TSR loaded) frown

GW-BASIC 2.01.01 (from DEC 1984) with Bad Robots source (medium resolution):


------------------------------------------------------------

Cursor artefacts in a high resolution REGIS-powered game (EMPIRE.EXE). Cursor should blink. Please ignore the wrong Hz value in screen 2 (already corrected).


Edited by Bavarese (12/05/16 06:20 PM)

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#108128 - 12/05/16 05:13 PM Re: Requirements? [Re: rfka01]
Haze Offline
Very Senior Member

Registered: 05/27/04
Posts: 1305
I know you say ignore the wrong hz, but there is a MAME issue whereby if both screens aren't of the SAME hz you will have problems with screens not updating properly, including graphic trails.. you don't say what you corrected it to

so unless the correct frequency for both is the same (60?) and that's what you're running both at you'll run into core issues.
_________________________
http://mamedev.emulab.it/haze/

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#108129 - 12/05/16 06:05 PM Re: Requirements? [Re: rfka01]
Bavarese Offline
Senior Member

Registered: 04/29/12
Posts: 140
Loc: Germany
Is there a proper work around?

For example, two separate screens or switching to "Graphics Output" via GUI?

I remember your warning, and in fact the refresh is 50 or 60 Hz at text screen 1 (above) and 59.999 / 29.999 (interlaced) at bottom.

The cursor (trail) problem even occurs if i disable screen 1 completely. A custom layout with "side by side", "over under", "Text only" and "Graphics only" options is there.

An assumption made near line 1210 / CCHAR (cursor characteristics) @ Upd7220.cpp makes me confident it is no simple artefact.

For completeness, here the complete bug list included in the driver. Help is very much appreciated.

Code:
BUGS
- GDC diagnostic disk fails on 9 of 13 tests (tests 4 and 6 - 13). 

Details
a. (Rainbow driver) : interaction between DEC's external hardware and the NEC 7220 isn't fully understood (see page 173 of AA-AE36A)
   It is also unclear what port $50 actually does when it 'synchronizes R-M-W cycles' between NEC and DEC hardware.
   For now, we provide sane defaults for both vector and bitmap units without disturbing colors, display mode(s) or the NEC 7220.
b. the HBLANK / VBLANK ratio is plainly wrong (QUICK TEST / subtest #6),
c. IRQs are flagged as 'erratic' (QUICK TEST / subtest #12). 
d. (7220) : incorrect fifo stati are handed out (GDC reports FIFO_EMPTY instead of _FULL when QUICK TEST #4 floods the queue)
e. (7220) : RDAT with MOD 2 used extensively here, but unimplemented (modes other than 0 weren't documented by NEC or INTEL) 

Programs with initialization / redraw / reentrance problems (invocation order after reset matters, at least in emulation):
- CANON (high resolution + vectors), Solitaire (SOLIT.EXE) and GDEMO (from GRPHCS.ARC, interactive graphics interpreter '85),
  plus the Monitor Aligment Test (from the GDC test disk). 

Graphical games that work well: MMIND (MasterMind, after BMP logo), PACMAN, SCRAM, (G)OTELO.

UNIMPLEMENTED:
// - Rainbow 100 A palette quirks (2 bit palette... applies to certain modes only)

UNKNOWN IMPLEMENTATION DETAILS:
// 1. READBACK (hard copy programs like JOBSDUMP definitely use it. See also GDC diagnostics).  VRAM_R ?

// 2. UNVERIFIED DIVIDER (31.188 Mhz / 32) is at least close to 1 Mhz (as on the VT240, which uses a very similar design)

// 3. UPD7220 / CORE oddities: 
// 3.1. occasional redraw problems (only when screen 1 runs at 60 Hz and screen 2 at 29.99 Hz interlaced = HIRES ?).
// Quote from Haze: "if you have 2 screens running at different refresh rates one of them won't update properly
//                  (the partial update system gets very confused because it expects both the screens to end at the same time
//                  and if that isn't the case large parts of one screen end up not updating at all)

   3.2 pixels are stretched out too wide at 384 x 240 (not fixable in Rainbow driver, -keepaspect seems to have no effect)



Edited by Bavarese (12/05/16 06:22 PM)

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#108361 - 01/06/17 11:21 PM Re: Requirements? [Re: rfka01]
Bavarese Offline
Senior Member

Registered: 04/29/12
Posts: 140
Loc: Germany
The aspect ratio problem is fixed and all known ClikClok versions are supported.

Time for new ventures... Corvus hard disks (of type B/H) are now working under CP/M 1.x



I admit, that's a bit old skool smile

Once upon a time Corvus supported MS-DOS 2.x and CP/M 2.2 too. But are there any driver disks left?

There must have been an XDRIVE.SYS -DOS- device driver (mentioned in a Corvus PDF someone posted here).

Definitive -chs parameters for Corvus B/H hard disks are hard to come by, too (needed for Chdman)...

Al Kossow, to the rescue?


Edited by Bavarese (01/06/17 11:46 PM)

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