A Blitter question....

[DarkLord]

So I've been reading this book I got off of Amazon last week, per a reference
at Atari Age. It's called "Faster Than Light: The Atari ST and the 16 Bit Revolution".

I'm about halfway through it and it's been pretty good so far.

One section did make me pause though. When the author covered the STacy,
he mentioned it's blitter chip. Well, label me blind (and with some justification)
but I've never noticed a blitter chip on my STacy. I have some pictures of my
STacy's motherboard when I was doing all of those upgrades back in 2013 and
I pulled them out but was unable to find anything. So I googled the Wiki entry
for the STacy and it says it has a blitter chip.

So I fired my STacy up and there's no blitter chip entry in the drop-down menu.
Now I'm using TOS v3.06 (modified TT030 TOS) and since the TT doesn't have a
blitter chip, I figured maybe TOS v3.06 wouldn't show one, even if there. So I
ran SysInfo. It reports no blitter as well, but I'm still wondering if that's maybe
because it's reading the TOS version?

So I used the Pak 68/3's compatibility mode to boot up to a plain, 8mhz, TOS v1.4
(identical to a stock, unmodified STacy) machine. I checked the drop-down menu
again, but still no blitter entry. I ran SysInfo again, but it also (still) reports no
blitter. It's completely grayed out.

So I thought I'd run this past the knowledgeable people here. Does the STacy have
a blitter or not?

Thanks gang.

[czietz]

Well, the STacy schematic (on dev-docs) does not show a Blitter, either. I've seen some web sites claiming that the Blitter was integrated in the video chip ("Shadow"). But that's clearly impossible, given that the Shadow lacks the requisite signals.

[Cyprian]

So I fired my STacy up and there's no blitter chip entry in the drop-down menu.

you can check whether it is present with those applications:

A) It should shows "3F" or "40" if the BLiTTER is present.
viewtopic.php?t=40138

B) "BLIT_H6A.zip" should shows black stripes if the BLiTTER is present
viewtopic.php?p=313181#p313181

[DoG]

Well, the STacy schematic (on dev-docs) does not show a Blitter, either. I've seen some web sites claiming that the Blitter was integrated in the video chip ("Shadow"). But that's clearly impossible, given that the Shadow lacks the requisite signals.

Atari computer museum states that is has it as you pointed out.

[DarkLord]

Well, the STacy schematic (on dev-docs) does not show a Blitter, either. I've seen some web sites claiming that the Blitter was integrated in the video chip ("Shadow"). But that's clearly impossible, given that the Shadow lacks the requisite signals.

That's interesting. I hadn't thought to look at the schematics - thanks!

[DarkLord]

you can check whether it is present with those applications:

A) It should shows "3F" or "40" if the BLiTTER is present.
viewtopic.php?t=40138

B) "BLIT_H6A.zip" should shows black stripes if the BLiTTER is present
viewtopic.php?p=313181#p313181

Okay, I downloaded Blitt ST (the first one). Running it from C:\ results
in a 2 bomb error (not fatal, returns to the desktop) when running in
TOS v3.06 mode.

Dropping down to compatibility mode (8mhz and TOS v1.4, stock STacy)
mode results in a quick flash, with nothing else I can see displayed,
before also returning to the desktop.

Thanks.

[Cyprian]

ok,

A) "BLITTST.zip" - 2 bomb means bus error - it seems there is no blitter. did you run it in compatibility mode (8mhz and TOS v1.4, stock STacy)?

B) "BLIT_H6A.zip" - in which video mode do you see that "quick flash"? that app needs TV (ST-LOW/MID mode). Can you take a picture? did you run it in compatibility mode (8mhz and TOS v1.4, stock STacy)?

[DarkLord]

Oh, my bad Cyprian - I didn't make my last post clear.

I ran the first app twice, once in full Pak 68/3 mode
and the 2nd time in compatibility mode (8mhz, TOS v1.4).

First pass (full Pak mode, TOS v3.06) gave the 2 bomb error.

Second pass (8mhz, TOS v1.4) gave the brief flash.

I never attempted using the 2nd app.

Thanks.

[Cyprian]

ok, wrong behavior in both cases, suggesting that there is no the BLiTTER there (or it is somehow deactivated at the hardware level?)

Would it be possible to run and take a photo "BLIT_H6A.zip" in 8mhz, TOS v1.4?

[DarkLord]

Okay, that's a no-go as well.

I'm assuming this is supposed to run in color modes?

I tried it in mono/hi-res, fed to one of those nice Dell 27"
monitors that's pretty good with the ST's video ranges,
using the STacy's external monitor port, using one of those
UBE switches.

STacy01.JPG

STacy03.JPG

STacy02.JPG

STacy04.JPG

In mono, 8mhz, TOS v1.4, it did pretty much like the 2nd
test in my post above - desktop kinda flashed a bit then
nothing.

I switched it to color/med-res and ran it. Same thing, but
man, it really scrambled up the picture!.

Next, I set it to color/low-res and it pretty much did the
same thing but this time I was able to see 2 bombs display
for brief moment before disappearing.

Now...just to be thorough and because I was curious, I
switched back to full Pak 68/3 mode, 40mhz and TOS v3.06.

In mono/hi-res, again a brief flash and then the desktop.

In color/med-res, brief flash and the desktop is really, really
messed up.

STacy05.JPG

In color/low-res, I got the 2 bombs again.

STacy07.JPG

BTW, I don't know if it would make a difference or not, but
I do have a 40mhz 68882 FPU onboard the Pak 68/3.

Well, that's all I can think of to do for the moment. My
conclusion, based on these tests and the schematics, is
that the STacy doesn't have a blitter chip.

Unless it's one of those instances where *some* STacy's do
and some don't? <shrugs>

Thanks for all the help.

[Arne]

Just plug in the testkit (set to ST) and check if the menu offers a Blitter test.
I have three Stacys and all of them have the same mainboard layout. So I really doubt that there are mainboards that provide a Blitter (socket).
And as czietz pointed out: Shadow is not capable of doing Blitter ops as it cannot act as a busmaster (no /BR, /BG, /BGACK, CPU address bus)!

[Cyprian]

I switched it to color/med-res and ran it. Same thing, but
man, it really scrambled up the picture!.

that's ok, The OS is in a different video mode than the SHIFTER/SHADOW.
The application crashed, therefore it did not restore the original video mode.

ok the test B) also "BLIT_H6A.zip" bombs out. Two bombs means a bus error, this is when the CPU touching the hardware register area which is not valid/used. Therefore I'm 99% sure that there is no the BLiTTER there.

I wonder if maybe there was another STacy revision with the BLiTTER, e.g. integrated with the GST MCU

[czietz]

I wonder if maybe there was another STacy revision with the BLiTTER, e.g. integrated with the GST MCU

??? The STacy never had a GST MCU. It's based on the ST (not STE) line, i.e., it has separate GLUE, MCU, etc.

[Cyprian]

that was just an example


BTW
I wonder what for is the chip TC552557BPL-10 = LCD VRAM-Chip - 62256 (32k x on the STacy schematic. Is it somehow offload the the main RAM from video activity?

[czietz]

I wonder what for is the chip TC552557BPL-10 = LCD VRAM-Chip - 62256 (32k x on the STacy schematic. Is it somehow offload the the main RAM from video activity?

The LCD needs to be driven differently and with different timing than the monochrome CRT. But the GLUE, MMU (and Shifter) chipset is not flexible enough to generate that timing. Hence, the Shadow chip takes the video data (in the same way as the Shifter) but buffers it into the VRAM, in order to read it back to drive the LCD. Hence, the VRAM contains a copy of the screen memory.

[Cyprian]

@czietz ok, thanks for the explanation

[DarkLord]

So we're going with "no blitter".

Thanks for the help guys.