Hacking CSA Mandelzoom to work on a B008

X-Received	by 2002:a05:6214:1bcd:b0:4af:646a:9793 with SMTP id m13-20020a0562141bcd00b004af646a9793mr519172qvc.94.1664409116042; Wed, 28 Sep 2022 16:51:56 -0700 (PDT)
X-Received	by 2002:a37:395:0:b0:6cd:cca6:4b8a with SMTP id 143-20020a370395000000b006cdcca64b8amr388714qkd.573.1664409115648; Wed, 28 Sep 2022 16:51:55 -0700 (PDT)
Path	csiph.com!1.us.feeder.erje.net!feeder.erje.net!usenet.blueworldhosting.com!feed1.usenet.blueworldhosting.com!peer03.iad!feed-me.highwinds-media.com!news.highwinds-media.com!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail
Newsgroups	comp.sys.transputer
Date	Wed, 28 Sep 2022 16:51:55 -0700 (PDT)
Injection-Info	google-groups.googlegroups.com; posting-host=82.31.125.46; posting-account=l3olFwkAAAB7_YlbF47jpoRgdTkZ-iGF
NNTP-Posting-Host	82.31.125.46
User-Agent	G2/1.0
MIME-Version	1.0
Message-ID	<d7189237-e335-44c2-b763-e77cee63fdaan@googlegroups.com> (permalink)
Subject	Hacking CSA Mandelzoom to work on a B008
From	Tom Stepleton <stepleton@gmail.com>
Injection-Date	Wed, 28 Sep 2022 23:51:56 +0000
Content-Type	text/plain; charset="UTF-8"
Content-Transfer-Encoding	quoted-printable
X-Received-Bytes	2908
Xref	csiph.com comp.sys.transputer:452

Show key headers only | View raw

There, that's more like it:
https://photos.app.goo.gl/d4HmNMHEwW8Jry6x8

As noted in the previous thread and elsewhere, the CSA Mandelbrot program won't work on a B008 as it's natively configured. The program freezes when it attempts to execute some code on the T212 installed on the board.

I've been studying the worm program that distributes the software to the Transputers, and there's a pretty easy (if kludgy) alteration to the source code that sidesteps this problem. Just above this line: https://github.com/axelmuhr/T-Mandel/blob/master/FLBOOT.TAL#L179

add these instructions:

ldl LOOPA
adc -1
cj @R3

What it's doing is pretty unsophisticated. Note in this diagram: http://transputer.net/mg/b008ug/figure/096/fig01.png
that the T212 is reached from TRAM0 (natively the host TRAM) via Link 1. Since the software distributing worm starts from TRAM0, the T212 is discovered right away and joins the Transputer network assembled by the worm.

The Transputer network is never represented completely in one place --- instead, each node records its upstream node ("BOOTIN", the neighbour that "infected" the node with the worm) and up to three downstream nodes ("BOOTOUT[0..2]"). It identifies these nodes by the memory location of their channel control word (if that's confusing to any reader, you can replace it with "link ID" to get the idea).

What my hack does is prevent Link 1 from being the downstream connection to ANY node. It's quite crude, and it prevents the network from getting the most out of some topologies, but there is no ordinary topology you can set up on a B008 in its default hardware configuration that will fail to operate --- provided you stick to 32-bit Transputers.

I'll share my notes on the worm program before long.

--Tom

Back to comp.sys.transputer | Previous | Next — Next in thread | Find similar

Thread

Hacking CSA Mandelzoom to work on a B008 Tom Stepleton <stepleton@gmail.com> - 2022-09-28 16:51 -0700
  Re: Hacking CSA Mandelzoom to work on a B008 Tom Stepleton <stepleton@gmail.com> - 2022-09-28 16:54 -0700

csiph-web