Proper name of Spectrum 128
| colours = 15 (2 per 8×8 cell)
The ZX Spectrum +3 was released on the 16th of May 1987. It is a significant redesign from the original [[ZX Spectrum
+ 128K|"Toastrack" 128K]] and [[ZX Spectrum +2|Grey +2]] models, with additional memory paging capabilities to support [[CP/M]] and additional ROM containing the [[+3DOS]] disc operating system code. The +3 has an integrated 3″ single sided floppy disc drive.
The "Black +2" appeared soon after with an integrated tape drive. Housed in a slightly modified version of the +2 case moulding cast in black plastic instead of grey.
=====Common hardware specifications=====
* Processor: Zilog Z80A microprocessor clocked at 3.5469MHz.
64KB ROM. 2×32KB EPROM arranged in 4 pages of 16KB.* RAM: 128KB of Dynamic RAM, arranged in 8 pages of 16KB.* Graphics: 256 × 192 pixels, 16 colours, attribute based. See [[Spectrum Video Modes]].
* Sound: AY-3-8912 3 channel, 8 octave Programmable Sound Generator and "beeper". Modulated onto video signal.
* Keyboard: 58 plastic keys with metal springs, operating a plastic membrane.
==Timings and Contention==
The contention and ram timings on the +3 and Black +2 differ significantly from earlier models due to the redesigned [[The Amstrad gate array|gate array]]. Timing patterns and memory contention are described in detail in the [[Contended memory#
Black + 2 (+ 2A/B) and + 3|contended memory]] article.
The memory space is divided into four
16k pages and can be used in two ways; "Standard paging mode" and "Special paging mode".
Paging is controlled by performing I/O writes to ports 0x1ffd and 0x7ffd.
====Standard paging mode====
64k of ROM and 128k of RAM can be paged into the memory space as shown in the diagram below:
<!-- table of memory pages -->