4
edits
ZX Spectrum 16K/48K: Difference between revisions
Jump to navigation
Jump to search
no edit summary
m (Avoid redirect) |
No edit summary |
||
| Line 81: | Line 81: | ||
=== Issue 3 === | === Issue 3 === | ||
The Issue 3 Spectrum included a new, uprated speaker with louder output. | The Issue 3 Spectrum included a new, uprated speaker with louder output. This is buffered by a new transistor on the PCB (TR7, ZTX450) instead of being directly driven by the ULA. | ||
Starting with the Issue 3, a low power 6C ULA was used, with changes to the handling of the EAR socket which caused compatibility problems. The "spider" fix was integrated into board. | Starting with the Issue 3, a low power 6C ULA was used, with changes to the handling of the EAR socket which caused compatibility problems. The "spider" fix was integrated into board. | ||
The Issue 3 was the first issue to be sold in the Spectrum+. | The Issue 3 was the first issue to be sold in the Spectrum+. | ||
=== Issue 4 === | |||
The Issue 4A and 4B Spectrums improve ULA memory signal timing by delaying /RAS through two previously unused gates in IC24. It's important that ULA 6C001E-7 is used in these models. | |||
=== Issue 5 === | |||
This is described in the service manual, however none are thought to exist in the wild. | |||
=== Issue 6 === | === Issue 6 === | ||
The Issue | The Issue 6 includes changes required if using the [[Saga ULA]]. So far, only one such machine has been found. It also includes the ZX8401 IC (also found as the PCF1306P) to consolidate the six 74LS IC's that control all of the memory access logic in previous issues. | ||
== External links == | == External links == | ||