From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,HTML_MESSAGE, MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: from minnie.tuhs.org (minnie.tuhs.org [45.79.103.53]) by inbox.vuxu.org (OpenSMTPD) with ESMTP id 9f0b0493 for ; Thu, 19 Dec 2019 00:20:53 +0000 (UTC) Received: by minnie.tuhs.org (Postfix, from userid 112) id DF63A9BC26; Thu, 19 Dec 2019 10:20:52 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id D2CC59BBF9; Thu, 19 Dec 2019 10:20:29 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=pass (1024-bit key; unprotected) header.d=planet.nl header.i=@planet.nl header.b="APWBmbdJ"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id AFFAF9BBF9; Thu, 19 Dec 2019 10:20:22 +1000 (AEST) Received: from cpsmtpb-ews06.kpnxchange.com (cpsmtpb-ews06.kpnxchange.com [213.75.39.9]) by minnie.tuhs.org (Postfix) with ESMTP id BAA399B92E for ; Thu, 19 Dec 2019 10:20:20 +1000 (AEST) Received: from cpsps-ews27.kpnxchange.com ([10.94.84.193]) by cpsmtpb-ews06.kpnxchange.com with Microsoft SMTPSVC(7.5.7601.17514); Thu, 19 Dec 2019 01:20:19 +0100 X-Brand: 7abm2Q== X-KPN-SpamVerdict: e1=0;e2=0;e3=0;e4=(e1=10;e3=10;e2=11;e4=10);EVW:Whi te;BM:NotScanned;FinalVerdict:Clean X-CMAE-Analysis: v=2.3 cv=YbfDGDZf c=1 sm=1 tr=0 cx=a_idp_e a=dZ5u/0G9QtS9WKCcNUBnHQ==:117 a=soxbC+bCkqwFbqeW/W/r+Q==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=x1i13A_MHe4A:10 a=pxVhFHJ0LMsA:10 a=cggplEk1AAAA:8 a=8zvtdvGnAAAA:8 a=UxsAKQ9BAAAA:8 a=a-gnvHiv817n45FmkLEA:9 a=QEXdDO2ut3YA:10 a=9LIKAnKgWzagveUe:21 a=_W_S_7VecoQA:10 a=TyGOKPG1VZVQ-HZz1HdS:22 a=Q-xCa1abX5qBlSYUmlcr:22 a=d_mXNDjUptLsIMHJEirF:22 X-CM-AcctID: kpn@feedback.cloudmark.com Received: from smtp.kpnmail.nl ([195.121.84.13]) by cpsps-ews27.kpnxchange.com over TLS secured channel with Microsoft SMTPSVC(8.5.9600.16384); Thu, 19 Dec 2019 01:20:19 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=planet.nl; s=planet01; h=to:date:subject:mime-version:content-type:message-id:from; bh=LATww/LPGKWDUyPiUkdMhTacHRlQAeagYqrqcVaYxGY=; b=APWBmbdJaJn0jP7XgPSXYSvKa1To6zv1KppgEYb3Co6OWRA6AwuagTzpyLOxPE7yDJGhES1QUfepY gqcwR+RiSs/sIUvfsw0rghwFzvoYW0s5qVIcyH8DE+Ser4HjruJiY+z9KhAGfVBeHP+kdpz2scciaY hCNpvRCBb4sH6Yt8= X-KPN-VerifiedSender: Yes X-CMASSUN: 33|oN0QwkMfl6He0fIbFqyaWl1smyRkYR/fNmvSoTPJOkK4cR+8zOYHw8GTRqhImhO Z7/NracLAwvig8eMkFJEX3w== X-Originating-IP: 80.101.112.122 Received: from mba1.fritz.box (unknown [80.101.112.122]) by smtp.kpnmail.nl (Halon) with ESMTPSA id 567b7d25-21f5-11ea-b3da-005056998788; Thu, 19 Dec 2019 01:20:19 +0100 (CET) From: Paul Ruizendaal Message-Id: <744AB73C-9970-450E-8B1A-5BACF9FE3E11@planet.nl> Content-Type: multipart/alternative; boundary="Apple-Mail=_7B565711-124A-4039-AD2E-FEC179623E07" Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) Date: Thu, 19 Dec 2019 01:20:18 +0100 In-Reply-To: <6be1d013-2323-9850-03fd-c4014c4a69e7@e-bbes.com> To: emanuel stiebler References: <6be1d013-2323-9850-03fd-c4014c4a69e7@e-bbes.com> X-Mailer: Apple Mail (2.3445.9.1) X-OriginalArrivalTime: 19 Dec 2019 00:20:19.0505 (UTC) FILETIME=[1887F210:01D5B602] X-RcptDomain: minnie.tuhs.org Subject: Re: [TUHS] Blit source X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: TUHS main list Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" --Apple-Mail=_7B565711-124A-4039-AD2E-FEC179623E07 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 > On Dec 16, 2019, at 7:25 AM, emanuel stiebler wrote: >=20 > On 2019-12-15 21:45, Paul Ruizendaal wrote: >> I=E2=80=99m looking for source code of the original Blit as described = here: >> http://doc.cat-v.org/bell_labs/blit/blit.pdf >=20 > Thanks for trying again. It pops up on this list every few years, but > still no schematics (2002, 2012) ... >=20 > Cheers Have you seen the 5620 schematics on bitsavers? http://bitsavers.org/pdf/att/5620/schematic/5620_logic.pdf = Of course it is not the Blit schematics, but it looks like a close = derivative. When comparing the Hardware & Software Tradeoffs paper with = the schematics and the theory of operation notes at the back, it would = seem to me that much of it is (near) identical to the 68K Blit. - The video timing circuit was probably identical (also see the figures = at the back with exact timing specifications). - The memory grid was probably (near) identical - maybe changed slightly = for the option to use 256Kx1 drams. - The arbitration circuit may have been redesigned, but it looks like = the bus arbitration of the M68K was not all that different from the = Bellmac. A memory cycle takes 11 ticks of the 32.7 MHz pixel clock, or = about 335ns. This is consistent with the numbers mentioned in the Blit = papers (e.g. the display using about 30% of memory bandwidth, etc.). - The mouse movement circuit appears unchanged from the Blit paper, with = a two-phase motion signal counted for the first 4 bits in a PAL and the = rest in a TTL counter Some things are of course different (beyond the different CPU). The 5620 = has an I/O expansion port and a bit of non-volatile memory, neither of = which is mentioned in the Blit papers. The memory map is totally = different and the protection for null pointer dereference appears gone. The 2x 6850 UART appears to be replaced by a single 2681 programmable = DUART. The button signals are routed through the additional parallel I/O = bits that this chip provides, which also takes care of interrupt = generation. According to the Blit papers there were several other = versions of the Blit before the final design was arrived upon. Maybe = earlier designs used a 2681 DUART as well, or its close cousin SCN68681. = Maybe the earlier version of button.c could work with both. If this is = true, it would stand to reason that the various features of the = 2681/68681 were replicated with the two 6850=E2=80=99s and some = supporting circuitry. This hypothesis seems to fit with some of aiju=E2=80= =99s observations in the =E2=80=9Cmmap=E2=80=9D information file = included with the Blit emulator (e.g. accessing register 25 and 27, the = timer/counter and its use for sound generation). The Blit promotional video that AT&T put on youtube in 2012 has a brief = shot (at 0:45) of the logic board. This appears to show two 24 pin = packages in the bottom center of the board, which are in all likelihood = the 6850=E2=80=99s. There is no 40 pin package (i.e. no 2681/68681 chip) = on that board. --Apple-Mail=_7B565711-124A-4039-AD2E-FEC179623E07 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
On = Dec 16, 2019, at 7:25 AM, emanuel stiebler <emu@e-bbes.com> = wrote:

On 2019-12-15 21:45, Paul Ruizendaal wrote:
I=E2=80=99m looking for = source code of the original Blit as described here:
http://doc.cat-v.org/bell_labs/blit/blit.pdf

Thanks for trying again. It pops = up on this list every few years, but
still no schematics = (2002, 2012) ...

Cheers

Have you seen the 5620 schematics on bitsavers?

http://bitsavers.org/pdf/att/5620/schematic/5620_logic.pdf<= /div>

Of course it = is not the Blit schematics, but it looks like a close derivative. When = comparing the Hardware & Software Tradeoffs paper with the = schematics and the theory of operation notes at the back, it would seem = to me that much of it is (near) identical to the 68K Blit.

- The video timing = circuit was probably identical (also see the figures at the back with = exact timing specifications).
- The memory grid was = probably (near) identical - maybe changed slightly for the option to use = 256Kx1 drams.
- The arbitration circuit may have = been redesigned, but it looks like the bus arbitration of the M68K was = not all that different from the Bellmac. A memory cycle takes 11 ticks = of the 32.7 MHz pixel clock, or about 335ns. This is consistent with the = numbers mentioned in the Blit papers (e.g. the display using about 30% = of memory bandwidth, etc.).
- The mouse movement = circuit appears unchanged from the Blit paper, with a two-phase motion = signal counted for the first 4 bits in a PAL and the rest in a TTL = counter

Some = things are of course different (beyond the different CPU). The 5620 has = an I/O expansion port and a bit of non-volatile memory, neither of which = is mentioned in the Blit papers. The memory map is totally different and = the protection for null pointer dereference appears gone.

The 2x 6850 UART appears = to be replaced by a single 2681 programmable DUART. The button signals = are routed through the additional parallel I/O bits that this chip = provides, which also takes care of interrupt generation. According to = the Blit papers there were several other versions of the Blit before the = final design was arrived upon. Maybe earlier designs used a 2681 DUART = as well, or its close cousin SCN68681. Maybe the earlier version of = button.c could work with both. If this is true, it would stand to reason = that the various features of the 2681/68681 were replicated with the two = 6850=E2=80=99s and some supporting circuitry. This hypothesis seems to = fit with some of aiju=E2=80=99s observations in the =E2=80=9Cmmap=E2=80=9D= information file included with the Blit emulator (e.g. accessing = register 25 and 27, the timer/counter and its use for sound = generation).

The= Blit promotional video that AT&T put on youtube in 2012 has a brief = shot (at 0:45) of the logic board. This appears to show two 24 pin = packages in the bottom center of the board, which are in all likelihood = the 6850=E2=80=99s. There is no 40 pin package (i.e. no 2681/68681 chip) = on that board.

= --Apple-Mail=_7B565711-124A-4039-AD2E-FEC179623E07--