Editing Timex Sinclair 1000 (section)

==Timex Sinclair 1500 {{anchor|ts1500}}<!-- for redirect to here -->==
{{Infobox information appliance
| name = Timex Sinclair 1500
| image = Timex-Sinclair-1500-White-BG.jpg
| caption = 
| developer = [[Timex Sinclair]]
| manufacturer = [[Timex Corporation]]
| type = [[Home computer]]
| releasedate = {{Start date and age|1983}}
| price = {{Inflation|US|79.95|1983|fmt=eq|orig=yes|cursign=$}}
| discontinued = 1983
| os = [[Sinclair BASIC]]
| power = 9V DC
| cpu = [[Z80]] at 3.25&nbsp;MHz
| memory = 16&nbsp;[[kilobyte|KB]] (32&nbsp;KB max)
| predecessor = Timex Sinclair 1000
| successor = [[Timex Sinclair 2068]]
| related = 
| compatibility = [[ZX81]]
| display = Monochrome display on television, NTSC; 24 lines × 32 characters; 64 × 48 pixels semigraphics mode
| aka = T/S 1500
}}

The '''T/S 1500''' was an upgraded T/S 1000 with a better keyboard and 16&nbsp;KB dynamic RAM, introduced in 1983.<ref name="auto">{{Cite news |last=Mace |first=Scott |date=November 14, 1983 |title=The Industry - Q&A: Dan Ross |volume=5 |pages=109 |work=InfoWorld |issue=46 |url=https://books.google.com/books?id=wS8EAAAAMBAJ&dq=%22Timex+Sinclair%22+-wikipedia&pg=PA109}}</ref><ref name="mitchell19830906">{{cite news | url=https://news.google.com/newspapers?id=gn0hAAAAIBAJ&sjid=tYoFAAAAIBAJ&pg=5584%2C3561802 | title=A summer-CES report | work=Boston Phoenix | date=1983-09-06 | accessdate=10 January 2015 | author=Mitchell, Peter W. | pages=4}}</ref> Timex Sinclair (TMX Portugal) designed the T/S 1500 and offered it to the Timex Corporation. The design utilized the T/S 2000 prototype (ZX Spectrum-like) silver cases that weren't previously used because of the launch of the [[T/S 2068]]. 

The machine was sold in the United States, [[Canada]] and [[Portugal]]. It replaced the earlier machine's [[ZX81]]-like case with a silver [[ZX Spectrum]]-like case, the same ZX Spectrum rubber keyboard, and a custom [[Gate array|ULA]]. 

The T/S 1500 did not incorporate the [[Ferranti]] ULA but instead uses a 68-pin custom logic chip by NCR.<ref>{{cite web |title=Timex Sinclair 1500 |url=https://www.timexsinclair.com/computers/timex-sinclair-1500/index.html |website=timexsinclair.com |access-date=4 March 2025}}</ref> The T/S 1500 used a standard television for its display, "broadcasting" on either [[Band I#North America|channel 2 or 3]]. It defaulted to TV channel 2, but if {{keypress|3}} was pressed on the keyboard within a few seconds of turning the computer on, it changed to channel 3 instead. 

Although the T/S 1500 came with 16&nbsp;KB internal RAM, an external 16&nbsp;KB RAM pack could be added for a total of 32&nbsp;KB RAM. A few keyboard commands (<code>POKE</code>) were required for the system to recognize the additional memory space (the ROMs RAM size check at 'boot' only assumed 16k max and set RAMTOP system variable accordingly for this).

The T/S 1500 sold for $80{{r|mitchell19830906}} and was not a commercial success because of its late launch long after the success of the T/S 1000. The T/S 1000's successor, the [[Timex Sinclair 2068|T/S 2068]], was already available.<ref name="auto" />
===Bugs===
There are two little-known software differences between the T/S 1000 and T/S 1500.<ref>{{Cite web |title=Ask HN: What bug(s) make "LPRINT 0.00001" output "0.0XYZ1"? {{!}} Hacker News |url=https://news.ycombinator.com/item?id=21363892 |access-date=2023-01-20 |website=news.ycombinator.com}}</ref>

On the T/S 1000 and ZX81, the command:

 LPRINT 0.00001

results in the Timex printer outputting <code>0.0XYZ1</code>. This well-known fault was corrected on the T/S 1500.

The T/S 1000 runs the following loop correctly, but the T/S 1500 does not; it makes one fewer iteration than it should.
<syntaxhighlight lang="basic">
10 FOR I=0 TO 1 STEP 0.25
20 PRINT I
30 NEXT I
</syntaxhighlight>