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So how many bytes can actually be put in the buffer?

a little basic program to run:

and taking the printer offline and running it, it will stop after 64901:

[Linked Image from i.imgur.com]

releasing the printer and holding reset for a couple of seconds will clear the buffer where it resumes printing:

[Linked Image from i.imgur.com]

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Somehow my numbers seemed off so I wanted to see exactly how many bytes can be held in the Buffered Grappler buffer:

Code
   0  ?"PLEASE TAKE THE PRINTER OFF LINE" : ? : ? : INPUT "EXPECTED SIZE (16384, 32768, 65536) :";ES
   1 GOTO 100
   5 A$ = STR$(I) + CHR$(13): FOR J = 1 TO LEN(A$):?MID$(A$,J,1);:NEXT: FOR J = 1 TO S - LEN(A$) - 1 : ? CHR$(C); : NEXT : RETURN
  100 PR # 1
  105 S = 250 : C = 32  : ES = (INT(ES / S) - 1) * S
  110 FOR I = 0 TO ES-1 STEP S : GOSUB 5 : NEXT
  126 S = 10 : C = ASC(".")
  130 FOR I = ES TO ES + 500  STEP S:  GOSUB 5 : NEXT
  135 REM CHR$(13) GOES TO PRINTER AS TWO CHARACTERS 0D 0A

r6 and r7 contain FFFF which is 65535 bytes

[Linked Image from i.imgur.com]

and it looks like we have 65535

[Linked Image from i.imgur.com]

and 32k buffer gets 32767

[Linked Image from i.imgur.com]

and 16k buffer gets 16383

[Linked Image from i.imgur.com]

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What’s the crystal next to the microcontroller on the Buffered Grappler+ and what exactly is it connected to? The 1982 Bufferboard schematics show a 6MHz crystal used to generate the 8048 clock on Version 1 boards while the 7M clock from the edge connector is used on Version 2 boards. The 1982 Buffered Grappler+ schematics don’t show any crystal at all. However, the crystal is present in photos of Buffered Grappler+ boards with UVEPROM microcontroller/host ROM as well as the later ones with mask ROM parts, so it wasn’t a particularly late addition.

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Hi Vas,

tilting the board up I see it says
NYMPH
6.000
NMP060

looks like one leg connects to pin 2 of the 8048 socket and the other leg connects to pin 3

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I guess we need two versions of the card, a 6MHz one and one that uses the host 7M clock. Interesting that they changed back to 6MHz at some point after going the other way with the Version 2 Bufferboard.

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markings on the back of Buffered Grappler+ card:

ORANGE MICRO INC., 1983
ASSY NO, 72 BGP 00001 REV A

PART NO. 95PCB00003


yes, that is interesting,

https://archive.org/details/TheBufferboardManualAppleIIGrapplerEpsonAppleParallel/page/n3/mode/2up

the bufferboard manual schematic shows the mention of 6M and 7M clocks:

[Linked Image from i.imgur.com]

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One little tidbit about the regular Grappler Plus: more recent versions had a 374 at U10

Quote
https://support.apple.com/kb/TA36748?locale=en_US

Apple IIGS: Grappler Plus cards
This article has been archived and is no longer updated by Apple.

Older Grappler Plus cards are not necessarily Apple IIGS compatible. Some of
the older interface cards malfunction because of timing changes made to the
IIGS slots, even though these changes were within Apple's specifications. The
Grappler Plus card was designed before Apple even had those timing
specifications.

On the Grappler Plus card at location U10, if the chip there is a 74LS373,
then you have an old card and should contact Orange Micro. A 74LS374 is at
U10 on the recent card.

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Ok I thought I'd try to redump the 8048 on the Buffered Grappler+, and did it around 10 times and kept getting the exact same results.

Therefore, something must be wrong. Since it's powered by a USB cable, I dug around and found a different usb power supply and guess what - the read is slightly different.

hexdump -C and writing it to two files to compare looks like there's the two differences: FF => FD and FF => FE

Code
diff origdump.txt newdump.txt 
24c24
< 00000170  01 fd 39 f9 02 02 47 a9  1d ff 39 f9 02 02 8a ee  |..9...G...9.....|
---
> 00000170  01 fd 39 f9 02 02 47 a9  1d fd 39 f9 02 02 8a ee  |..9...G...9.....|
49c49
< 00000330  0a f2 47 ff ce 96 38 cd  fd 4e 96 00 0a f2 41 64  |..G...8..N....Ad|
---
> 00000330  0a f2 47 fe ce 96 38 cd  fd 4e 96 00 0a f2 41 64  |..G...8..N....Ad|

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Yep, the second change fixes a 16-bit decrement in a loop where it’s waiting to see if the reset key(s) are being helddown for long enough. I hope there aren’t other bad bits lurking…

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Originally Posted by Golden Child
One little tidbit about the regular Grappler Plus: more recent versions had a 374 at U10
That just replaces a transparent latch with an edge-triggered one. Nothing for us to worry about there.

Are manuals and schematics available for the original Grappler or the ProGrappler?

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