Beside the logic analyzer
UNIBUS extender
This is specfici to UBUS-PDP-11's, but similar tool are neede to work on every computer: card extender.
Normally, logic cards are mountedside.-by-side in some kind of logic cage.
Arangement then is so that there's a force air flow over all cards..
<foto: voller card cage>
In this situationm, there's no space to clip on any kind of logic probes.
So DEC (and other vendors) procied "extender boards". This boards allow to mount cards outside the case for easy access.
Major draw backs of those extenders are
- signal pathes are longer now, so some new critical timing failures may occur.
- forced air cooling is disturbed. Not only the card under test runs without moved air now. And since the computer case must be opened, all other card may suffer from reduced cooling.
A DEC PDP-11/34 CPU <sogar> consists of two cards (data path and control). To access but cards simultaniosly, one cards must be placed on one extender, and the second card must even be placed on two!
Such a setting is quite unreliable. So on any new bug its wise to test wether the bug dissappears if the cards are run regualry inside the case without extenders.
Multimeter
There's not much to say. Any is fine: it just must beep on contact and show the voltage more or less precisely.
Logic probe
A simple device: needs 5V, which come from the devce under test. has a LED for LOW level, and one for HIGH level. No singal menas: not a proper TTÖL level. I uses it to read micro store bits, from a haltd machine , read signals is 20x times faster than using the LA. I alos found some defectiveve chips, where the driver
<fotos>
unsolder station
Well, after find a defective chip, you must get it out of its board. And also important: you must be able to harvest replacement ICs from sapre boards.
programmable power suply
The typical low price laboratory power supply can not deliver more than 5A. This is not enough to power a CPU card with over 100 TTL chips, if you want to run it outside its card cage.
Also I do "burn-in tests" by powering cards with jut +5V supply outside the computer. If the power supply is remote constrolled, you can program pweor-up/power.down cycles to simualte a real pwoer cycles.
EPROM reader/burner
I have an old ALL-07 whcih was build in the 1990's and still has support for most of the old PROMs. It evan has a component tester for 74xx ICs.
Oscilloscope
The LA maps every signal to 0 or 1. In I case of defcetove chips, you can expect all kind of physical dsitortions, so sometimes you must see the elctricial signals isntead of the lgoica ones.
The scope should have at least the same badnwidht as the LA: 200MHz. This gets to costly .. but donÄt go below 100MHz.
A good LA has a trigger output signal to: if he catches a trigger signal, the trigger output can be connecto to the scope externa trigger input, so you ccan catch synchroized logic and analog signals.
In some difficult problems, the LA probe changed the voltage level of the device under. A LA probe as aan typical impedance of a few 100kOHm, while a scope probe is in the 100Mohn range., So using a scope will show the real signals.