Nascom 2 RAM board construction notes
| page 5 |
It is reported that certain boards harbour an etching fault
whereby the decoupling capacitor for IC8 fails to connect with
the ground rail. It is reasonable to check for this fault and
to correct it if possible, although its consequences are
unlikely to be noticeable and are nothing to do with ‘memory
plague’. |
| page 12 |
et seq The memory test programs are written for the T2 monitor
and will not operate under Nas-sys 1. It is recommended that
the advice given on page 15 is followed and that a small test
program is written to test for ‘plague’ only if this condition
is suspected. The printed test programs are not specifically
designed to reveal plague.” (And probably won’t. Ed.) |
(Editors note: We do not like these unspecified references to ‘memory
plague’ as unsuspecting purchasers of Nascom 2s would have no idea what
is meant; only hardened Nascom 1 owners who read these newsletters will
be in the know. For new Nascom 2 owners, ‘memory plague’ is a condition
which arises in some memories due to noise and speed problems, and
leads to unreliable memory performance (not to be confused with suspect
chips). Several notes have been published about ‘memory plague’, and we
hope to collect them all together and publish a compendium of memory
mods in the
next issue.
Memory plague may be detected in a Nascom 2 by
the failure of the Basic to initialize properly, or the ‘free memory’
message giving silly or inconsistent answers after initialization. This
is not the same as the total failure of the Basic to initialize if the
memory construction notes are followed to the letter (having missed the
small errata); where the constructor is instructed to connect decode
pad 12 to P5, thus enabling the RAM board EPROM block to page F,
thereby totally disabling half of the Basic.)
“8K Basic programming manual
| page 16 |
The list of reserved words should include DEEK and Monitor. |
| page 24 |
The second sentence should read: ‘It uses locations 1000H to
113EH (4414) ....... .’ The second sentence should read:
“Locations 113FH to DFFFH are therefore ....... .’” |
(Editors note: Well thats what it said, and we couldn’t understand it
either, so we looked it up in a manual that was a couple of months old.
That didn’t make sense either, suggesting that the Basic used 8K+ of
workspace, so after a little investigation we think page 24 should read
as follows:
“Nascom Basic leaves locations between 0C80H (3200 decimal) and 0FFFH
(4095 decimal) inclusive for use by user machine code routines. It uses
locations 1000H (4096) to 10F9H (4345) inclusive for workspace and
resides in E000H (-8192) to FFFFH (-1) inclusive. Locations 10FAH
(4346) to DFFFH (-8193) inclusive are therfore available for the users’
Basic program and data.”)
| “page 26 |
program 1 line 40: the word ‘to’ should be in upper case.” |
For a manual the size of the Nascom 2 manual you must expect a
few mistakes but we bet they haven’t all been found (we haven’t tried
looking yet), but if you come across any please let us know. so that
they can be ammended in later manuals. That way new users of Nascom 2
might not run into some of the problems that have been experienced.