Dear Editor

For a TS2068 version of Dave Wood‘s HIGH LINE NUMBERS (SYNTAX Dec.83 p4) you need only add two PEEKs which locate the line number bytes in memory. Line numbers store as high byte followed by low, reversed compared to most other 16-bit quantities.

On your TS2068, enter as line 1 the line which will be last in the listing (highest line number). Then use this direct command:

LET a=PEEK 23635+PEEK 23636*256:
POKE a,(hi byte): POKE a+1,(lo byte)

Write down decimal values of POKEd lines (high byte*256+low byte); any line numbered higher than 16383 (63*256+255) won’t show on-screen.

To add more high-number lines, enter the next highest line in the listing as line 1. As long as RUN or CLEAR have not been used after defining a in memory, use the direct command:

POKE a,(hi byte):POKE a+1,(lo byte)

The highest possible line number is 32767 (hi byte=127 & lo byte=255).

Only lines numbered less than 16383 will function with a normal RUN command, GO TO, or GO SUB. Lines numbered from 16384 to 32767 will function only by a direct RUN or GO TO and then execute only the statement contained in that line–useful only as a curiosity or to store listings off-screen. When lines numbered 1-9999 are pushed off-screen by a line numbered from 16384 to 32767, and a GO TO is then made to the high-numbered line, it will be processed along with the normal lines which follow it in the listing order.

To EDIT the last line entered, if it doesn’t show on-screen, enter the direct command POKE a,1. Lines 10,000 to 16383 may be brought down with EDIT, re-numbered to less than 10,000, revised, and POKEd back to a high number. You can calculate the location of line number bytes after the first line in a listing, but otherwise the only way to EDIT a line POKEd above 9999 is to delete all preceding lines in the listing, both on- and off-screen.

For locating start of 2nd line:

1 LET a=PEEK 23635+PEEK 23636*256
2 PRINT "Demo"
3 FOR n=a TO a+1000
   4 IF PEEK n=13 THEN LET a=n+1:                                 GO TO 10
5 NEXT n
10 POKE a,10
20 LIST

In comment on the “New image” Timex now has for their 1-800-24-TIMEX customer support service, in contrast to the rather vague responses most of us received in the past, they very helpfully provided me with a schematic, I/O map, and pin-out as well as an approximate availability date on the forthcoming TS2000 Advanced Programming Concepts Manual. I greatly appreciate this kind of support and, judging from the amount of time it took me to get a free line on the TIMEX number, I am sure there are many others.

Robert Hartung, Palmyra, NY

SYNTAX (Aug.82 p19) describes the illegal line number 3E00H (15872) as the marker for the top of the GOSUB stack in ZX/TS machines. The Spectrum uses the same marker, but we don’t know about the 2068.–KO

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MAINTAINING THE ZX81

Calling 1-800-24-TIMEX seems an exercise in futility. After 4 days of 20-30 calls per day, I gave up. Only twice did I get a ring. On these two occasions the nice recorded voice told me “everyone is busy, please be patient, someone will soon help you.” In about ten seconds, the line disconnected.

I was trying to call about a replacement ULA chip for my TS1000, out of warranty, modified circuit board system. I guess I zapped it with body electrostatic charge, although it broke out while typing in a program.

Testing the system using an oscilloscope I found no clocked signals associated with ROMCS and RAMCS (6.5 Mhz clock was OK).

Since contacting TIMEX was a total failure, I then spent about $30.00 on phone calls, eventually locating a TS1000. Believe me, the inventory of TS1000 computers in the US is very close to zero. If Syntax readers want to obtain a “spare” for their upgraded ZX/TS systems, I advise them to act now. Sunset Electronics (415/665-8330), still has a few at $29.95 as of this writing. Some twenty other suppliers I called have none and cannot get more. For $29.95 plus shipping I can get a spare set of ULA and ROM chips for my future needs. I suspect a spare ULA chip would, itself, cost up to $20.00, if one could be found.

US replacements for British transistors: Sylvania ECG-123AP replaces ZTX-313; ECG-391 replaces ZTX-750 and ZTX-752. Almost any “signal diode,” such as 1N34A, will replace any diode on the board. The crystal located in the circuit between pin 35 of the ULA chip and pin 26 of the Z80 CPU, can be replaced with an ordinary JAN 6.5 MHz crystal (smallest metal can crystal with axial leads). All other parts on the circuit board, except the ULA and ROM chips, may be purchased off the shelf.

Bill Jones, Panama City, FL

Use 1N914 or 1N4148 diodes for the higher forward drop of Silicon.–KO

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I think your readers would appreciate the answers to the following questions:

1) Why does the Timex 2040 printer emit heat from its top vent even though I have pressed the “OFF” button and haven’t used the printer in days?

2) The new Timex 2068 computer only seems to have 38K available for programming (16K “BASIC” and 22K “VARS”); why?

3) What peripherals can be used safely with the Timex 1500 computer? (e.g. when I plugged in my 16K Sinclair Rampak the computer went blank and I had to send it back to the supplier. I hear there are problems if you use a Memopak 64K and other hardware not manufactured by Timex).

Wm. McConaghey, Pembroke Pines, FL

TS2040 printers emit heat when off because the switch doesn’t turn off the 24V printhead power.

Most computers use some RAM to perform functions that permit your programs to operate. Sharon Aker reports that the Commodore 64 also allows only 38911 bytes for users compared with 38652 in the TS2068. Page 254 of the user’s manual shows how a 2068 uses memory. I know of no 16K BASIC limit in 2068’s, but SYNTAX has discussed it at length for ZX/TS operation, including ways to get around it. (Sep.82 p13; SQ Summer 83 p47 & Nov.83 p12)

TS1500 computers will operate with any accessory that doesn’t use RAMCS to disable the internal RAM. On 1500’s, RAMRM moves the internal RAM to 32-48K and leaves it active. Sinclair RAMpaks do work, and Byte-Back memories and modules operate (SYNTAX Nov.83 p14). We hear that some 1500’s would not drive Timex printers, and the 2040 printer will destroy the data-line timing. See SYNTAX Nov.83 p2 for details of the fix for 2040-generated problems–KO